diff --git a/Tests/AliasTarget/CMakeLists.txt b/Tests/AliasTarget/CMakeLists.txt
index 47ccbdc9b..f9ae03ad6 100644
--- a/Tests/AliasTarget/CMakeLists.txt
+++ b/Tests/AliasTarget/CMakeLists.txt
@@ -8,7 +8,7 @@ set(CMAKE_CXX_STANDARD 98)
 # template support also need a flag to use the newer C++ library.
 if (CMAKE_CXX_COMPILER_ID STREQUAL HP AND
     CMAKE_CXX98_STANDARD_COMPILE_OPTION STREQUAL "+hpxstd98")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -AA")
+  string(APPEND CMAKE_CXX_FLAGS " -AA")
 endif ()
 
 # Clang/C2 in C++98 mode cannot properly handle some of MSVC headers
diff --git a/Tests/CMakeOnly/CheckCXXSymbolExists/CMakeLists.txt b/Tests/CMakeOnly/CheckCXXSymbolExists/CMakeLists.txt
index 9528aa357..f058c19fb 100644
--- a/Tests/CMakeOnly/CheckCXXSymbolExists/CMakeLists.txt
+++ b/Tests/CMakeOnly/CheckCXXSymbolExists/CMakeLists.txt
@@ -50,7 +50,7 @@ else ()
 endif ()
 
 if (CMAKE_COMPILER_IS_GNUCXX)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O3")
+  string(APPEND CMAKE_CXX_FLAGS " -O3")
   unset(CSE_RESULT_O3 CACHE)
   message(STATUS "Testing with optimization -O3")
 
diff --git a/Tests/CMakeOnly/CheckStructHasMember/CMakeLists.txt b/Tests/CMakeOnly/CheckStructHasMember/CMakeLists.txt
index f06d5c34d..a58450515 100644
--- a/Tests/CMakeOnly/CheckStructHasMember/CMakeLists.txt
+++ b/Tests/CMakeOnly/CheckStructHasMember/CMakeLists.txt
@@ -77,7 +77,7 @@ endforeach()
 set(CMAKE_TRY_COMPILE_CONFIGURATION ${CMAKE_BUILD_TYPE})
 
 if (CMAKE_COMPILER_IS_GNUCC)
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O3")
+    string(APPEND CMAKE_C_FLAGS " -O3")
     unset(CSHM_RESULT_O3 CACHE)
     unset(CSHM_RESULT_O3_C CACHE)
     unset(CSHM_RESULT_O3_CXX CACHE)
diff --git a/Tests/CMakeOnly/CheckSymbolExists/CMakeLists.txt b/Tests/CMakeOnly/CheckSymbolExists/CMakeLists.txt
index 765657712..7f01463c0 100644
--- a/Tests/CMakeOnly/CheckSymbolExists/CMakeLists.txt
+++ b/Tests/CMakeOnly/CheckSymbolExists/CMakeLists.txt
@@ -39,7 +39,7 @@ else ()
 endif ()
 
 if (CMAKE_COMPILER_IS_GNUCC)
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O3")
+  string(APPEND CMAKE_C_FLAGS " -O3")
   unset(CSE_RESULT_O3 CACHE)
   message(STATUS "Testing with optimization -O3")
 
diff --git a/Tests/CMakeTests/ModuleNoticesTest.cmake.in b/Tests/CMakeTests/ModuleNoticesTest.cmake.in
index 8ecebd338..7bea0af48 100644
--- a/Tests/CMakeTests/ModuleNoticesTest.cmake.in
+++ b/Tests/CMakeTests/ModuleNoticesTest.cmake.in
@@ -35,7 +35,7 @@ foreach(module ${all_modules})
   message(STATUS "module: ${module}")
   file(READ "${dir}/${module}" module_content)
   if(NOT "${module_content}" MATCHES "${notice_regex}")
-    set(notice_missing "${notice_missing}  ${module}\n")
+    string(APPEND notice_missing "  ${module}\n")
   endif()
 endforeach()
 
diff --git a/Tests/CMakeTests/WhileTest.cmake.in b/Tests/CMakeTests/WhileTest.cmake.in
index cc22978ce..90665448e 100644
--- a/Tests/CMakeTests/WhileTest.cmake.in
+++ b/Tests/CMakeTests/WhileTest.cmake.in
@@ -2,13 +2,13 @@ set(NUMBERS "")
 set(COUNT 0)
 
 while(COUNT LESS 200)
-    set(NUMBERS "${NUMBERS} ${COUNT}")
+    string(APPEND NUMBERS " ${COUNT}")
     set(COUNT "2${COUNT}")
 
     set(NCOUNT 3)
     while(NCOUNT LESS 31)
-        set(NUMBERS "${NUMBERS} ${NCOUNT}")
-        set(NCOUNT "${NCOUNT}0")
+        string(APPEND NUMBERS " ${NCOUNT}")
+        string(APPEND NCOUNT "0")
     endwhile()
 endwhile()
 
diff --git a/Tests/CPackComponentsDEB/RunCPackVerifyResult-components-lintian-dpkgdeb-checks.cmake b/Tests/CPackComponentsDEB/RunCPackVerifyResult-components-lintian-dpkgdeb-checks.cmake
index d51650c0a..f1391cd73 100644
--- a/Tests/CPackComponentsDEB/RunCPackVerifyResult-components-lintian-dpkgdeb-checks.cmake
+++ b/Tests/CPackComponentsDEB/RunCPackVerifyResult-components-lintian-dpkgdeb-checks.cmake
@@ -41,7 +41,7 @@ if(LINTIAN_EXECUTABLE)
                                   FILENAME "${_f}"
                                   ERROR_REGEX_STRINGS "${STRINGS_TO_AVOID}")
 
-    set(lintian_output_errors_all "${lintian_output_errors_all}${lintian_output_errors}")
+    string(APPEND lintian_output_errors_all "${lintian_output_errors}")
   endforeach()
 
   if(NOT "${lintian_output_errors_all}" STREQUAL "")
diff --git a/Tests/CPackComponentsDEB/RunCPackVerifyResult.cmake b/Tests/CPackComponentsDEB/RunCPackVerifyResult.cmake
index b4e567c9e..2f9e2fc92 100644
--- a/Tests/CPackComponentsDEB/RunCPackVerifyResult.cmake
+++ b/Tests/CPackComponentsDEB/RunCPackVerifyResult.cmake
@@ -126,7 +126,7 @@ function(lintian_check_specific_errors output_errors)
     string(REGEX MATCHALL "${_s}" "_TMP_CHECK_ERROR" "${lintian_output}")
 
     if(NOT "${_TMP_CHECK_ERROR}" STREQUAL "")
-      set(ERROR_ACC "${ERROR_ACC}\nlintian: ${_f}: output contains an undesirable regex:\n\t${_TMP_CHECK_ERROR}")
+      string(APPEND ERROR_ACC "\nlintian: ${_f}: output contains an undesirable regex:\n\t${_TMP_CHECK_ERROR}")
     endif()
   endforeach()
 
diff --git a/Tests/CTestUpdateBZR.cmake.in b/Tests/CTestUpdateBZR.cmake.in
index 8fb1d3483..da181d2ed 100644
--- a/Tests/CTestUpdateBZR.cmake.in
+++ b/Tests/CTestUpdateBZR.cmake.in
@@ -4,7 +4,7 @@
 #-----------------------------------------------------------------------------
 # Test in a directory next to this script.
 get_filename_component(TOP "${CMAKE_CURRENT_LIST_FILE}" PATH)
-set(TOP "${TOP}/@CTestUpdateBZR_DIR@")
+string(APPEND TOP "/@CTestUpdateBZR_DIR@")
 
 # Include code common to all update tests.
 include("@CMAKE_CURRENT_SOURCE_DIR@/CTestUpdateCommon.cmake")
diff --git a/Tests/CTestUpdateCVS.cmake.in b/Tests/CTestUpdateCVS.cmake.in
index 277b3a603..5389bdf51 100644
--- a/Tests/CTestUpdateCVS.cmake.in
+++ b/Tests/CTestUpdateCVS.cmake.in
@@ -4,7 +4,7 @@
 #-----------------------------------------------------------------------------
 # Test in a directory next to this script.
 get_filename_component(TOP "${CMAKE_CURRENT_LIST_FILE}" PATH)
-set(TOP "${TOP}/@CTestUpdateCVS_DIR@")
+string(APPEND TOP "/@CTestUpdateCVS_DIR@")
 set(UPDATE_NOT_GLOBAL 1)
 set(UPDATE_MAYBE Updated{CTestConfig.cmake})
 
diff --git a/Tests/CTestUpdateCommon.cmake b/Tests/CTestUpdateCommon.cmake
index 458e42743..61aa13b94 100644
--- a/Tests/CTestUpdateCommon.cmake
+++ b/Tests/CTestUpdateCommon.cmake
@@ -84,9 +84,9 @@ function(check_updates build)
   set(MSG "")
   if(MISSING)
     # List the missing entries
-    set(MSG "${MSG}Update.xml is missing expected entries:\n")
+    string(APPEND MSG "Update.xml is missing expected entries:\n")
     foreach(f ${MISSING})
-      set(MSG "${MSG}  ${f}\n")
+      string(APPEND MSG "  ${f}\n")
     endforeach()
   else()
     # Success
@@ -96,9 +96,9 @@ function(check_updates build)
   # Report the result
   if(EXTRA)
     # List the extra entries
-    set(MSG "${MSG}Update.xml has extra unexpected entries:\n")
+    string(APPEND MSG "Update.xml has extra unexpected entries:\n")
     foreach(f ${EXTRA})
-      set(MSG "${MSG}  ${f}\n")
+      string(APPEND MSG "  ${f}\n")
     endforeach()
   else()
     # Success
@@ -112,9 +112,9 @@ function(check_updates build)
     if(UPDATE_LOG_FILE)
       file(READ ${UPDATE_LOG_FILE} UPDATE_LOG LIMIT ${max_update_xml_size})
       string(REPLACE "\n" "\n  " UPDATE_LOG "${UPDATE_LOG}")
-      set(MSG "${MSG}Update log:\n  ${UPDATE_LOG}")
+      string(APPEND MSG "Update log:\n  ${UPDATE_LOG}")
     else()
-      set(MSG "${MSG}No update log found!")
+      string(APPEND MSG "No update log found!")
     endif()
 
     # Display the error message
diff --git a/Tests/CTestUpdateGIT.cmake.in b/Tests/CTestUpdateGIT.cmake.in
index 46230cca3..7d0fa0fab 100644
--- a/Tests/CTestUpdateGIT.cmake.in
+++ b/Tests/CTestUpdateGIT.cmake.in
@@ -4,7 +4,7 @@
 #-----------------------------------------------------------------------------
 # Test in a directory next to this script.
 get_filename_component(TOP "${CMAKE_CURRENT_LIST_FILE}" PATH)
-set(TOP "${TOP}/@CTestUpdateGIT_DIR@")
+string(APPEND TOP "/@CTestUpdateGIT_DIR@")
 set(UPDATE_EXTRA Updated{module})
 
 # Include code common to all update tests.
diff --git a/Tests/CTestUpdateHG.cmake.in b/Tests/CTestUpdateHG.cmake.in
index c76bf9192..055d309e6 100644
--- a/Tests/CTestUpdateHG.cmake.in
+++ b/Tests/CTestUpdateHG.cmake.in
@@ -4,7 +4,7 @@
 #-----------------------------------------------------------------------------
 # Test in a directory next to this script.
 get_filename_component(TOP "${CMAKE_CURRENT_LIST_FILE}" PATH)
-set(TOP "${TOP}/@CTestUpdateHG_DIR@")
+string(APPEND TOP "/@CTestUpdateHG_DIR@")
 
 # Include code common to all update tests.
 include("@CMAKE_CURRENT_SOURCE_DIR@/CTestUpdateCommon.cmake")
diff --git a/Tests/CTestUpdateP4.cmake.in b/Tests/CTestUpdateP4.cmake.in
index f0420c42f..5eef9fbe3 100644
--- a/Tests/CTestUpdateP4.cmake.in
+++ b/Tests/CTestUpdateP4.cmake.in
@@ -5,7 +5,7 @@
 # Test in a directory next to this script.
 get_filename_component(TOP "${CMAKE_CURRENT_LIST_FILE}" PATH)
 set(P4_TOP "${TOP}")
-set(TOP "${TOP}/@CTestUpdateP4_DIR@")
+string(APPEND TOP "/@CTestUpdateP4_DIR@")
 
 # Include code common to all update tests.
 set(REPOSITORY_FILE_PREFIX "//ctest/")
@@ -48,9 +48,9 @@ if(UNIX)
   file(MAKE_DIRECTORY ${P4_ROOT})
 
   set(P4_SERVER "nohup '${P4D}' -d -r '${P4_ROOT}'")
-  set(P4_SERVER "${P4_SERVER} -L '${P4_ROOT}/p4.log'")
-  set(P4_SERVER "${P4_SERVER} -J '${P4_ROOT}/journal'")
-  set(P4_SERVER "${P4_SERVER} -p ${P4_PORT} >/dev/null 2>&1 &")
+  string(APPEND P4_SERVER " -L '${P4_ROOT}/p4.log'")
+  string(APPEND P4_SERVER " -J '${P4_ROOT}/journal'")
+  string(APPEND P4_SERVER " -p ${P4_PORT} >/dev/null 2>&1 &")
 
   message("Server command line: ${P4_SERVER}")
 
diff --git a/Tests/CTestUpdateSVN.cmake.in b/Tests/CTestUpdateSVN.cmake.in
index b757a441d..12a3526cb 100644
--- a/Tests/CTestUpdateSVN.cmake.in
+++ b/Tests/CTestUpdateSVN.cmake.in
@@ -4,7 +4,7 @@
 #-----------------------------------------------------------------------------
 # Test in a directory next to this script.
 get_filename_component(TOP "${CMAKE_CURRENT_LIST_FILE}" PATH)
-set(TOP "${TOP}/@CTestUpdateSVN_DIR@")
+string(APPEND TOP "/@CTestUpdateSVN_DIR@")
 set(UPDATE_GLOBAL_ELEMENTS SVNPath)
 
 # Include code common to all update tests.
diff --git a/Tests/Complex/CMakeLists.txt b/Tests/Complex/CMakeLists.txt
index a4a33c3c7..80cc2e3ba 100644
--- a/Tests/Complex/CMakeLists.txt
+++ b/Tests/Complex/CMakeLists.txt
@@ -95,7 +95,7 @@ endif()
 
 if(CMAKE_SYSTEM MATCHES "OSF1-V")
   if(NOT CMAKE_COMPILER_IS_GNUCXX)
-     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -timplicit_local -no_implicit_include ")
+     string(APPEND CMAKE_CXX_FLAGS " -timplicit_local -no_implicit_include ")
   endif()
 endif()
 
@@ -436,7 +436,7 @@ set(CMAKE_CXX_EXTENSIONS TRUE)
 # template support also need a flag to use the newer C++ library.
 if (CMAKE_CXX_COMPILER_ID STREQUAL HP AND
     CMAKE_CXX98_STANDARD_COMPILE_OPTION STREQUAL "+hpxstd98")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -AA")
+  string(APPEND CMAKE_CXX_FLAGS " -AA")
 endif ()
 
 # Clang/C2 in C++98 mode cannot properly handle some of MSVC headers
diff --git a/Tests/Complex/Executable/CMakeLists.txt b/Tests/Complex/Executable/CMakeLists.txt
index c30dcbc40..2a796298b 100644
--- a/Tests/Complex/Executable/CMakeLists.txt
+++ b/Tests/Complex/Executable/CMakeLists.txt
@@ -1,8 +1,8 @@
 #
 # Create exe.
 #
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DTEST_CXX_FLAGS")
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DTEST_C_FLAGS")
+string(APPEND CMAKE_CXX_FLAGS " -DTEST_CXX_FLAGS")
+string(APPEND CMAKE_C_FLAGS " -DTEST_C_FLAGS")
 
 # Create an imported target for if(TARGET) test below.
 add_library(ExeImportedTarget UNKNOWN IMPORTED)
diff --git a/Tests/Complex/Library/CMakeLists.txt b/Tests/Complex/Library/CMakeLists.txt
index f00cbd611..dbf806e4f 100644
--- a/Tests/Complex/Library/CMakeLists.txt
+++ b/Tests/Complex/Library/CMakeLists.txt
@@ -43,7 +43,7 @@ endif()
 #
 set(SharedLibrarySources sharedFile)
 add_library(CMakeTestLibraryShared SHARED ${SharedLibrarySources})
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DTEST_C_FLAGS")
+string(APPEND CMAKE_C_FLAGS " -DTEST_C_FLAGS")
 add_library(CMakeTestCLibraryShared SHARED testConly.c)
 define_property(
   TARGET PROPERTY FOO
diff --git a/Tests/Complex/VarTests.cmake b/Tests/Complex/VarTests.cmake
index 70b803a1e..9d35949af 100644
--- a/Tests/Complex/VarTests.cmake
+++ b/Tests/Complex/VarTests.cmake
@@ -180,5 +180,5 @@ endforeach()
 
 set(FOREACH_CONCAT "")
 foreach (INDEX a;b;c;d;e;f;g)
-  set(FOREACH_CONCAT "${FOREACH_CONCAT}${INDEX}")
+  string(APPEND FOREACH_CONCAT "${INDEX}")
 endforeach()
diff --git a/Tests/ComplexOneConfig/CMakeLists.txt b/Tests/ComplexOneConfig/CMakeLists.txt
index 9090ab5d2..1b833b241 100644
--- a/Tests/ComplexOneConfig/CMakeLists.txt
+++ b/Tests/ComplexOneConfig/CMakeLists.txt
@@ -88,7 +88,7 @@ endif()
 
 if(CMAKE_SYSTEM MATCHES "OSF1-V")
   if(NOT CMAKE_COMPILER_IS_GNUCXX)
-     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -timplicit_local -no_implicit_include ")
+     string(APPEND CMAKE_CXX_FLAGS " -timplicit_local -no_implicit_include ")
   endif()
 endif()
 
@@ -399,7 +399,7 @@ set(CMAKE_CXX_EXTENSIONS TRUE)
 # template support also need a flag to use the newer C++ library.
 if (CMAKE_CXX_COMPILER_ID STREQUAL HP AND
     CMAKE_CXX98_STANDARD_COMPILE_OPTION STREQUAL "+hpxstd98")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -AA")
+  string(APPEND CMAKE_CXX_FLAGS " -AA")
 endif ()
 
 # Clang/C2 in C++98 mode cannot properly handle some of MSVC headers
diff --git a/Tests/ComplexOneConfig/Executable/CMakeLists.txt b/Tests/ComplexOneConfig/Executable/CMakeLists.txt
index 4897b484a..f935aed1d 100644
--- a/Tests/ComplexOneConfig/Executable/CMakeLists.txt
+++ b/Tests/ComplexOneConfig/Executable/CMakeLists.txt
@@ -1,8 +1,8 @@
 #
 # Create exe.
 #
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DTEST_CXX_FLAGS")
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DTEST_C_FLAGS")
+string(APPEND CMAKE_CXX_FLAGS " -DTEST_CXX_FLAGS")
+string(APPEND CMAKE_C_FLAGS " -DTEST_C_FLAGS")
 
 # Create an imported target for if(TARGET) test below.
 add_library(ExeImportedTarget UNKNOWN IMPORTED)
diff --git a/Tests/ComplexOneConfig/Library/CMakeLists.txt b/Tests/ComplexOneConfig/Library/CMakeLists.txt
index f00cbd611..dbf806e4f 100644
--- a/Tests/ComplexOneConfig/Library/CMakeLists.txt
+++ b/Tests/ComplexOneConfig/Library/CMakeLists.txt
@@ -43,7 +43,7 @@ endif()
 #
 set(SharedLibrarySources sharedFile)
 add_library(CMakeTestLibraryShared SHARED ${SharedLibrarySources})
-set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DTEST_C_FLAGS")
+string(APPEND CMAKE_C_FLAGS " -DTEST_C_FLAGS")
 add_library(CMakeTestCLibraryShared SHARED testConly.c)
 define_property(
   TARGET PROPERTY FOO
diff --git a/Tests/ComplexOneConfig/VarTests.cmake b/Tests/ComplexOneConfig/VarTests.cmake
index 70b803a1e..9d35949af 100644
--- a/Tests/ComplexOneConfig/VarTests.cmake
+++ b/Tests/ComplexOneConfig/VarTests.cmake
@@ -180,5 +180,5 @@ endforeach()
 
 set(FOREACH_CONCAT "")
 foreach (INDEX a;b;c;d;e;f;g)
-  set(FOREACH_CONCAT "${FOREACH_CONCAT}${INDEX}")
+  string(APPEND FOREACH_CONCAT "${INDEX}")
 endforeach()
diff --git a/Tests/CustomCommand/CMakeLists.txt b/Tests/CustomCommand/CMakeLists.txt
index 268069d72..db57e19dc 100644
--- a/Tests/CustomCommand/CMakeLists.txt
+++ b/Tests/CustomCommand/CMakeLists.txt
@@ -376,8 +376,8 @@ foreach(arg ${CHECK_ARGS} "")
   set(ARG "${arg}")
   string(REPLACE "\\" "\\\\" ARG "${ARG}")
   string(REPLACE "\"" "\\\"" ARG "${ARG}")
-  set(EXPECTED_ARGUMENTS
-    "${EXPECTED_ARGUMENTS}  \"${ARG}\",
+  string(APPEND EXPECTED_ARGUMENTS
+    "  \"${ARG}\",
 ")
 endforeach()
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/check_command_line.c.in
@@ -476,7 +476,7 @@ add_custom_command(
 
 add_library(NormOutput "${gen_file}")
 
-set(gen_path "${gen_path}/bar")
+string(APPEND gen_path "/bar")
 set(gen_file "${gen_path}/bar.cxx")
 
 add_custom_command(
diff --git a/Tests/FindPackageTest/CMakeLists.txt b/Tests/FindPackageTest/CMakeLists.txt
index fadd0feef..d3e68bc5f 100644
--- a/Tests/FindPackageTest/CMakeLists.txt
+++ b/Tests/FindPackageTest/CMakeLists.txt
@@ -333,7 +333,7 @@ endif()
 # Choose a unique version.
 string(REGEX REPLACE "-.*$" "" version ${CMAKE_VERSION})
 string(RANDOM LENGTH 4 ALPHABET "0123456789" v)
-set(version "${version}.${v}")
+string(APPEND version ".${v}")
 
 message(STATUS "Preparing export(PACKAGE) test project")
 try_compile(EXPORTER_COMPILED
diff --git a/Tests/Fortran/CMakeLists.txt b/Tests/Fortran/CMakeLists.txt
index 12689824b..99fcc0a6d 100644
--- a/Tests/Fortran/CMakeLists.txt
+++ b/Tests/Fortran/CMakeLists.txt
@@ -188,7 +188,7 @@ if(TEST_MODULE_DEPENDS)
   if("${testf_BINARY_DIR}" MATCHES " ")
     # Our build tree has a space, so the build tool supports spaces.
     # Test using modules from a path with spaces.
-    set(External_BINARY_DIR "${External_BINARY_DIR} Build")
+    string(APPEND External_BINARY_DIR " Build")
   endif()
   add_custom_command(
     OUTPUT ${testf_BINARY_DIR}/ExternalProject
diff --git a/Tests/IncludeDirectories/CMakeLists.txt b/Tests/IncludeDirectories/CMakeLists.txt
index 523c4f71c..49205828f 100644
--- a/Tests/IncludeDirectories/CMakeLists.txt
+++ b/Tests/IncludeDirectories/CMakeLists.txt
@@ -39,9 +39,9 @@ if(WATCOM OR MSVC60)
   set(USE_FULLPATH FALSE)
 endif()
 if(USE_FULLPATH)
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} \"-I${CMAKE_BINARY_DIR}/Flags\"")
+  string(APPEND CMAKE_CXX_FLAGS " \"-I${CMAKE_BINARY_DIR}/Flags\"")
 else()
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -IFlags")
+  string(APPEND CMAKE_CXX_FLAGS " -IFlags")
 endif()
 
 include_directories(${CMAKE_BINARY_DIR}/IncDir)
diff --git a/Tests/MakeClean/CMakeLists.txt b/Tests/MakeClean/CMakeLists.txt
index 8ac624a63..fbd499534 100644
--- a/Tests/MakeClean/CMakeLists.txt
+++ b/Tests/MakeClean/CMakeLists.txt
@@ -34,7 +34,7 @@ endforeach()
 # Configure an executable to check that all the files are missing.
 set(CHECK_FILES)
 foreach(f ${TOCLEAN_FILES})
-  set(CHECK_FILES "${CHECK_FILES}      \"${f}\",\n")
+  string(APPEND CHECK_FILES "      \"${f}\",\n")
 endforeach()
 configure_file(${MakeClean_SOURCE_DIR}/check_clean.c.in
                ${MakeClean_BINARY_DIR}/check_clean.c @ONLY)
diff --git a/Tests/MathTest/CMakeLists.txt b/Tests/MathTest/CMakeLists.txt
index 34beaa0aa..ed2c7d48c 100644
--- a/Tests/MathTest/CMakeLists.txt
+++ b/Tests/MathTest/CMakeLists.txt
@@ -16,7 +16,7 @@ set(FILE_EXPRESSIONS "")
 foreach(expression
     ${expressions})
   math(EXPR expr "${expression}")
-  set(FILE_EXPRESSIONS "${FILE_EXPRESSIONS}TEST_EXPRESSION(${expression}, ${expr})\n")
+  string(APPEND FILE_EXPRESSIONS "TEST_EXPRESSION(${expression}, ${expr})\n")
 endforeach()
 
 configure_file(
diff --git a/Tests/Module/GenerateExportHeader/CMakeLists.txt b/Tests/Module/GenerateExportHeader/CMakeLists.txt
index 8b94ca786..56f0f28af 100644
--- a/Tests/Module/GenerateExportHeader/CMakeLists.txt
+++ b/Tests/Module/GenerateExportHeader/CMakeLists.txt
@@ -64,7 +64,7 @@ set(CMAKE_CXX_STANDARD 98)
 # template support also need a flag to use the newer C++ library.
 if (CMAKE_CXX_COMPILER_ID STREQUAL HP AND
     CMAKE_CXX98_STANDARD_COMPILE_OPTION STREQUAL "+hpxstd98")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -AA")
+  string(APPEND CMAKE_CXX_FLAGS " -AA")
 endif ()
 
 # Clang/C2 in C++98 mode cannot properly handle some of MSVC headers
@@ -103,7 +103,7 @@ endif()
 
 if (CMAKE_COMPILER_IS_GNUCXX OR (${CMAKE_CXX_COMPILER_ID} MATCHES Clang))
   # No need to clutter the test output with warnings.
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-deprecated-declarations")
+  string(APPEND CMAKE_CXX_FLAGS " -Wno-deprecated-declarations")
 endif()
 
 if(MSVC AND COMPILER_HAS_DEPRECATED)
diff --git a/Tests/Plugin/CMakeLists.txt b/Tests/Plugin/CMakeLists.txt
index 49ff317e8..f52b47954 100644
--- a/Tests/Plugin/CMakeLists.txt
+++ b/Tests/Plugin/CMakeLists.txt
@@ -32,7 +32,7 @@ set(CMAKE_CXX_STANDARD 98)
 # template support also need a flag to use the newer C++ library.
 if (CMAKE_CXX_COMPILER_ID STREQUAL HP AND
     CMAKE_CXX98_STANDARD_COMPILE_OPTION STREQUAL "+hpxstd98")
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -AA")
+  string(APPEND CMAKE_CXX_FLAGS " -AA")
 endif ()
 
 # Clang/C2 in C++98 mode cannot properly handle some of MSVC headers
diff --git a/Tests/Preprocess/CMakeLists.txt b/Tests/Preprocess/CMakeLists.txt
index b930f5653..15f0338ad 100644
--- a/Tests/Preprocess/CMakeLists.txt
+++ b/Tests/Preprocess/CMakeLists.txt
@@ -57,7 +57,7 @@ if(NOT BORLAND AND NOT PP_VS70)
   set(SEMICOLON "\;")
 endif()
 
-set(STRING_EXTRA "${STRING_EXTRA} ")
+string(APPEND STRING_EXTRA " ")
 
 if(NOT PP_BORLAND AND NOT PP_WATCOM)
   # Borland, WMake: multiple spaces
@@ -65,7 +65,7 @@ if(NOT PP_BORLAND AND NOT PP_WATCOM)
   # quoted strings when passing to the compiler.  It does not have
   # trouble passing to other tools, and the compiler may be directly
   # invoked from the command line.
-  set(STRING_EXTRA "${STRING_EXTRA} ")
+  string(APPEND STRING_EXTRA " ")
 endif()
 
 if(NOT PP_VS)
@@ -73,21 +73,21 @@ if(NOT PP_VS)
   # Visual Studio will not accept a comma in the value of a definition.
   # The comma-separated list of PreprocessorDefinitions in the project
   # file seems to be parsed before the content of entries is examined.
-  set(STRING_EXTRA "${STRING_EXTRA},")
+  string(APPEND STRING_EXTRA ",")
 endif()
 
 if(NOT PP_MINGW)
   # MinGW: &
   # When inside -D"FOO=\"a & b\"" MinGW make wants -D"FOO=\"a "&" b\""
   # but it does not like quoted ampersand elsewhere.
-  set(STRING_EXTRA "${STRING_EXTRA}&")
+  string(APPEND STRING_EXTRA "&")
 endif()
 
 if(NOT PP_MINGW)
   # MinGW: |
   # When inside -D"FOO=\"a | b\"" MinGW make wants -D"FOO=\"a "|" b\""
   # but it does not like quoted pipe elsewhere.
-  set(STRING_EXTRA "${STRING_EXTRA}|")
+  string(APPEND STRING_EXTRA "|")
 endif()
 
 if(NOT PP_BORLAND AND NOT PP_MINGW AND NOT PP_NMAKE)
@@ -95,13 +95,13 @@ if(NOT PP_BORLAND AND NOT PP_MINGW AND NOT PP_NMAKE)
   # When inside -D"FOO=\"a ^ b\"" the make tools want -D"FOO=\"a "^" b\""
   # but do not like quoted carrot elsewhere.  In NMake the non-quoted
   # syntax works when the flags are not in a make variable.
-  set(STRING_EXTRA "${STRING_EXTRA}^")
+  string(APPEND STRING_EXTRA "^")
 endif()
 
 if(NOT PP_BORLAND AND NOT PP_MINGW AND NOT PP_NMAKE)
   # Borland, MinGW: < >
   # Angle-brackets have funny behavior that is hard to escape.
-  set(STRING_EXTRA "${STRING_EXTRA}<>")
+  string(APPEND STRING_EXTRA "<>")
 endif()
 
 set(EXPR_OP1 "/")
@@ -122,7 +122,7 @@ if((NOT MSVC OR PP_NMAKE) AND
   # be written just '%'.  However nmake requires '%%' except when using
   # response files.  Currently we have no way to affect escaping based
   # on whether flags go in a response file, so we just have to skip it.
-  set(STRING_EXTRA "${STRING_EXTRA}%")
+  string(APPEND STRING_EXTRA "%")
   set(EXPR_OP1 "%")
 endif()
 
@@ -130,9 +130,9 @@ endif()
 # The XL compiler cannot pass unbalanced parens correctly to a tool
 # it launches internally.
 if(CMAKE_C_COMPILER_ID STREQUAL "XL")
-  set(STRING_EXTRA "${STRING_EXTRA}()")
+  string(APPEND STRING_EXTRA "()")
 else()
-  set(STRING_EXTRA "${STRING_EXTRA})(")
+  string(APPEND STRING_EXTRA ")(")
 endif()
 
 # General: \"
@@ -146,7 +146,7 @@ endif()
 #    internal tool to do preprocessing .
 if((PP_NMAKE OR PP_UMAKE) AND
     NOT CMAKE_C_COMPILER_ID STREQUAL "XL")
-  set(STRING_EXTRA "${STRING_EXTRA}\\\"")
+  string(APPEND STRING_EXTRA "\\\"")
 endif()
 
 # General: #
@@ -183,15 +183,15 @@ set(EXPR "x*y+!(x==(y+1*2))*f(x${EXPR_OP1}2)")
 
 if(NOT WATCOM)
   # Watcom does not support - or / because it parses them as options.
-  set(EXPR "${EXPR} + y/x-x")
+  string(APPEND EXPR " + y/x-x")
 endif()
 
 #-----------------------------------------------------------------------------
 
 # Inform the test if the debug configuration is getting built.
 # The NDEBUG definition takes care of this for release.
-set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -DPREPROCESS_DEBUG")
-set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -DPREPROCESS_DEBUG")
+string(APPEND CMAKE_C_FLAGS_DEBUG " -DPREPROCESS_DEBUG")
+string(APPEND CMAKE_CXX_FLAGS_DEBUG " -DPREPROCESS_DEBUG")
 
 # Inform the test if it built from Xcode.
 if(PP_XCODE)
@@ -265,7 +265,7 @@ add_custom_target(drive COMMAND Preprocess)
 
 # Configure the header file with the desired string value.
 if(SEMICOLON)
-  set(STRING_VALUE "${STRING_VALUE};")
+  string(APPEND STRING_VALUE ";")
 endif()
 configure_file(${Preprocess_SOURCE_DIR}/preprocess.h.in
                ${Preprocess_BINARY_DIR}/preprocess.h)
diff --git a/Tests/RunCMake/BuildDepends/check.cmake b/Tests/RunCMake/BuildDepends/check.cmake
index 26a9eb65d..c7b5c3d32 100644
--- a/Tests/RunCMake/BuildDepends/check.cmake
+++ b/Tests/RunCMake/BuildDepends/check.cmake
@@ -6,7 +6,7 @@ if(EXISTS ${RunCMake_TEST_BINARY_DIR}/check-debug.cmake)
   foreach(exe IN LISTS check_exes)
     execute_process(COMMAND ${exe} RESULT_VARIABLE res)
     if(NOT res EQUAL ${check_step})
-      set(RunCMake_TEST_FAILED "${RunCMake_TEST_FAILED}
+      string(APPEND RunCMake_TEST_FAILED "
  '${exe}' returned '${res}' but expected '${check_step}'
 ")
     endif()
@@ -16,15 +16,15 @@ if(EXISTS ${RunCMake_TEST_BINARY_DIR}/check-debug.cmake)
       set(lhs "${CMAKE_MATCH_1}")
       set(rhs "${CMAKE_MATCH_2}")
       if(NOT EXISTS "${lhs}")
-        set(RunCMake_TEST_FAILED "${RunCMake_TEST_FAILED}
+        string(APPEND RunCMake_TEST_FAILED "
  '${lhs}' missing
 ")
       elseif(NOT EXISTS "${rhs}")
-        set(RunCMake_TEST_FAILED "${RunCMake_TEST_FAILED}
+        string(APPEND RunCMake_TEST_FAILED "
  '${rhs}' missing
 ")
       elseif(NOT "${lhs}" IS_NEWER_THAN "${rhs}")
-        set(RunCMake_TEST_FAILED "${RunCMake_TEST_FAILED}
+        string(APPEND RunCMake_TEST_FAILED "
  '${lhs}' is not newer than '${rhs}'
 ")
       endif()
diff --git a/Tests/RunCMake/CMP0054/CMP0054-policy-while-scope.cmake b/Tests/RunCMake/CMP0054/CMP0054-policy-while-scope.cmake
index 2b22778b5..7fb836eb2 100644
--- a/Tests/RunCMake/CMP0054/CMP0054-policy-while-scope.cmake
+++ b/Tests/RunCMake/CMP0054/CMP0054-policy-while-scope.cmake
@@ -25,7 +25,7 @@ while(NOT LOOP_VAR STREQUAL "xx")
 
   cmake_policy(SET CMP0054 NEW)
 
-  set(LOOP_VAR "${LOOP_VAR}x")
+  string(APPEND LOOP_VAR "x")
 endwhile()
 
 while("FOO" STREQUAL BAR)
@@ -57,7 +57,7 @@ while(NOT LOOP_VAR STREQUAL "xx")
 
   cmake_policy(SET CMP0054 OLD)
 
-  set(LOOP_VAR "${LOOP_VAR}x")
+  string(APPEND LOOP_VAR "x")
 endwhile()
 
 if(NOT "FOO" STREQUAL BAR)
diff --git a/Tests/RunCMake/CPack/DEB/Helpers.cmake b/Tests/RunCMake/CPack/DEB/Helpers.cmake
index d05f11517..9b1be224d 100644
--- a/Tests/RunCMake/CPack/DEB/Helpers.cmake
+++ b/Tests/RunCMake/CPack/DEB/Helpers.cmake
@@ -40,13 +40,13 @@ function(getMissingShlibsErrorExtra FILE RESULT_VAR)
       set(error_extra " Extra: install files '${deb_install_files}'")
 
       if(deb_install_files_errors)
-        set(error_extra "${error_extra}; errors \"${deb_install_files_errors}\"")
+        string(APPEND error_extra "; errors \"${deb_install_files_errors}\"")
       endif()
 
       find_program(READELF_EXECUTABLE NAMES readelf)
 
       if(READELF_EXECUTABLE)
-        set(error_extra "${error_extra}; readelf \"\n")
+        string(APPEND error_extra "; readelf \"\n")
 
         # Only dynamically linked ELF files are included
         # Extract only file name infront of ":"
@@ -61,13 +61,13 @@ function(getMissingShlibsErrorExtra FILE RESULT_VAR)
               ERROR_VARIABLE err_
               OUTPUT_STRIP_TRAILING_WHITESPACE)
 
-            set(error_extra "${error_extra} name '${CMAKE_MATCH_1}'\n result '${result}'\n output '${output}'\n error '${err_}'\n")
+            string(APPEND error_extra " name '${CMAKE_MATCH_1}'\n result '${result}'\n output '${output}'\n error '${err_}'\n")
           endif()
         endforeach()
 
-        set(error_extra "${error_extra}\"")
+        string(APPEND error_extra "\"")
       else()
-        set(error_extra "${error_extra}; error readelf missing")
+        string(APPEND error_extra "; error readelf missing")
       endif()
     endif()
 
diff --git a/Tests/RunCMake/CPack/VerifyResult.cmake b/Tests/RunCMake/CPack/VerifyResult.cmake
index 6eab5312a..804766892 100644
--- a/Tests/RunCMake/CPack/VerifyResult.cmake
+++ b/Tests/RunCMake/CPack/VerifyResult.cmake
@@ -16,7 +16,7 @@ include("${src_dir}/${GENERATOR_TYPE}/${RunCMake_TEST}-ExpectedFiles.cmake")
 if(NOT EXPECTED_FILES_COUNT EQUAL 0)
   foreach(file_no_ RANGE 1 ${EXPECTED_FILES_COUNT})
     file(GLOB FOUND_FILE_${file_no_} RELATIVE "${bin_dir}" "${EXPECTED_FILE_${file_no_}}")
-    set(foundFiles_ "${foundFiles_};${FOUND_FILE_${file_no_}}")
+    string(APPEND foundFiles_ ";${FOUND_FILE_${file_no_}}")
     list(LENGTH FOUND_FILE_${file_no_} foundFilesCount_)
 
     if(foundFilesCount_ EQUAL 1)
@@ -45,7 +45,7 @@ if(NOT EXPECTED_FILES_COUNT EQUAL 0)
   # check that there were no extra files generated
   foreach(all_files_glob_ IN LISTS ALL_FILES_GLOB)
     file(GLOB foundAll_ RELATIVE "${bin_dir}" "${all_files_glob_}")
-    set(allFoundFiles_ "${allFoundFiles_};${foundAll_}")
+    string(APPEND allFoundFiles_ ";${foundAll_}")
   endforeach()
 
   list(LENGTH foundFiles_ foundFilesCount_)
diff --git a/Tests/RunCMake/RunCMake.cmake b/Tests/RunCMake/RunCMake.cmake
index fa0c98050..247855ac8 100644
--- a/Tests/RunCMake/RunCMake.cmake
+++ b/Tests/RunCMake/RunCMake.cmake
@@ -95,7 +95,7 @@ function(run_cmake test)
   endif()
   set(msg "")
   if(NOT "${actual_result}" MATCHES "${expect_result}")
-    set(msg "${msg}Result is [${actual_result}], not [${expect_result}].\n")
+    string(APPEND msg "Result is [${actual_result}], not [${expect_result}].\n")
   endif()
   foreach(o out err)
     string(REGEX REPLACE "\r\n" "\n" actual_std${o} "${actual_std${o}}")
@@ -107,7 +107,7 @@ function(run_cmake test)
         string(REGEX REPLACE "\n" "\n expect-${o}> " expect_${o}
           " expect-${o}> ${expect_std${o}}")
         set(expect_${o} "Expected std${o} to match:\n${expect_${o}}\n")
-        set(msg "${msg}std${o} does not match that expected.\n")
+        string(APPEND msg "std${o} does not match that expected.\n")
       endif()
     endif()
   endforeach()
@@ -122,7 +122,7 @@ function(run_cmake test)
   endif()
   if(msg AND RunCMake_TEST_COMMAND)
     string(REPLACE ";" "\" \"" command "\"${RunCMake_TEST_COMMAND}\"")
-    set(msg "${msg}Command was:\n command> ${command}\n")
+    string(APPEND msg "Command was:\n command> ${command}\n")
   endif()
   if(msg)
     string(REGEX REPLACE "\n" "\n actual-out> " actual_out " actual-out> ${actual_stdout}")
diff --git a/Tests/RunCMake/continue/ContinueWhile.cmake b/Tests/RunCMake/continue/ContinueWhile.cmake
index c1fa87ac2..f69993cc4 100644
--- a/Tests/RunCMake/continue/ContinueWhile.cmake
+++ b/Tests/RunCMake/continue/ContinueWhile.cmake
@@ -1,7 +1,7 @@
 message(STATUS "start")
 unset(iter)
 while(NOT "${iter}" STREQUAL "aaaaa")
-  set(iter "${iter}a")
+  string(APPEND iter "a")
   if("${iter}" STREQUAL "aaa")
     continue()
   endif()
diff --git a/Tests/RunCMake/if/IsDirectoryLong.cmake b/Tests/RunCMake/if/IsDirectoryLong.cmake
index 0e93be744..e6939ac10 100644
--- a/Tests/RunCMake/if/IsDirectoryLong.cmake
+++ b/Tests/RunCMake/if/IsDirectoryLong.cmake
@@ -1,6 +1,6 @@
 set(d "/long/path/to/directory")
 foreach(i RANGE 11)
-  set(d "${d}${d}")
+  string(APPEND d "${d}")
 endforeach()
 string(LENGTH "${d}" dl)
 if(IS_DIRECTORY "${d}/")
diff --git a/Tests/RunCMake/include_external_msproject/check_utils.cmake b/Tests/RunCMake/include_external_msproject/check_utils.cmake
index 408cadb78..5dd92f9cc 100644
--- a/Tests/RunCMake/include_external_msproject/check_utils.cmake
+++ b/Tests/RunCMake/include_external_msproject/check_utils.cmake
@@ -91,7 +91,7 @@ function(check_project test name guid type platform)
   if(guid)
     check_project_guid("${sln}" "${name}" "${guid}" passed_guid)
     if(NOT passed_guid)
-      set(failed "${failed}${sep}${name} solution has no project with expected GUID=${guid}")
+      string(APPEND failed "${sep}${name} solution has no project with expected GUID=${guid}")
       set(sep "\n")
     endif()
   else()
@@ -99,12 +99,12 @@ function(check_project test name guid type platform)
   endif()
   check_project_type("${sln}" "${name}" "${type}" passed_type)
   if(NOT passed_type)
-    set(failed "${failed}${sep}${name} solution has no project with expected TYPE=${type}")
+    string(APPEND failed "${sep}${name} solution has no project with expected TYPE=${type}")
     set(sep "\n")
   endif()
   check_custom_platform("${sln}" "${name}" "${platform}" passed_platform)
   if(NOT passed_platform)
-    set(failed "${failed}${sep}${name} solution has no project with expected PLATFORM=${platform}")
+    string(APPEND failed "${sep}${name} solution has no project with expected PLATFORM=${platform}")
     set(sep "\n")
   endif()
   set(RunCMake_TEST_FAILED "${failed}" PARENT_SCOPE)
diff --git a/Tests/RunCMake/install/DIRECTORY-MESSAGE_NEVER-check.cmake b/Tests/RunCMake/install/DIRECTORY-MESSAGE_NEVER-check.cmake
index 2c716e1e2..3605163a0 100644
--- a/Tests/RunCMake/install/DIRECTORY-MESSAGE_NEVER-check.cmake
+++ b/Tests/RunCMake/install/DIRECTORY-MESSAGE_NEVER-check.cmake
@@ -3,11 +3,11 @@ execute_process(COMMAND ${CMAKE_COMMAND} -P ${RunCMake_TEST_BINARY_DIR}/cmake_in
   OUTPUT_VARIABLE out ERROR_VARIABLE err)
 if(out MATCHES "-- Installing: [^\n]*prefix/dir")
   string(REGEX REPLACE "\n" "\n  " out "  ${out}")
-  set(RunCMake_TEST_FAILED
-    "${RunCMake_TEST_FAILED}Installation output was not quiet:\n${out}")
+  string(APPEND RunCMake_TEST_FAILED
+    "Installation output was not quiet:\n${out}")
 endif()
 set(f ${RunCMake_TEST_BINARY_DIR}/prefix/dir/empty.txt)
 if(NOT EXISTS "${f}")
-  set(RunCMake_TEST_FAILED
-    "${RunCMake_TEST_FAILED}File was not installed:\n  ${f}\n")
+  string(APPEND RunCMake_TEST_FAILED
+    "File was not installed:\n  ${f}\n")
 endif()
diff --git a/Tests/RunCMake/install/DIRECTORY-message-check.cmake b/Tests/RunCMake/install/DIRECTORY-message-check.cmake
index 857681fbc..c9de3ead1 100644
--- a/Tests/RunCMake/install/DIRECTORY-message-check.cmake
+++ b/Tests/RunCMake/install/DIRECTORY-message-check.cmake
@@ -7,13 +7,13 @@ set(expect "
 ")
 if(NOT out MATCHES "${expect}")
   string(REGEX REPLACE "\n" "\n  " out "  ${out}")
-  set(RunCMake_TEST_FAILED
-    "${RunCMake_TEST_FAILED}First install did not say 'Installing' as expected:\n${out}")
+  string(APPEND RunCMake_TEST_FAILED
+    "First install did not say 'Installing' as expected:\n${out}")
 endif()
 set(f ${RunCMake_TEST_BINARY_DIR}/prefix/dir/empty.txt)
 if(NOT EXISTS "${f}")
-  set(RunCMake_TEST_FAILED
-    "${RunCMake_TEST_FAILED}File was not installed:\n  ${f}\n")
+  string(APPEND RunCMake_TEST_FAILED
+    "File was not installed:\n  ${f}\n")
 endif()
 execute_process(COMMAND ${CMAKE_COMMAND} -P ${RunCMake_TEST_BINARY_DIR}/cmake_install.cmake
   OUTPUT_VARIABLE out ERROR_VARIABLE err)
@@ -23,6 +23,6 @@ set(expect "
 ")
 if(NOT out MATCHES "${expect}")
   string(REGEX REPLACE "\n" "\n  " out "  ${out}")
-  set(RunCMake_TEST_FAILED
-    "${RunCMake_TEST_FAILED}Second install did not say 'Up-to-date' as expected:\n${out}")
+  string(APPEND RunCMake_TEST_FAILED
+    "Second install did not say 'Up-to-date' as expected:\n${out}")
 endif()
diff --git a/Tests/RunCMake/install/DIRECTORY-message-lazy-check.cmake b/Tests/RunCMake/install/DIRECTORY-message-lazy-check.cmake
index c7e601880..433901201 100644
--- a/Tests/RunCMake/install/DIRECTORY-message-lazy-check.cmake
+++ b/Tests/RunCMake/install/DIRECTORY-message-lazy-check.cmake
@@ -7,18 +7,18 @@ set(expect "
 ")
 if(NOT out MATCHES "${expect}")
   string(REGEX REPLACE "\n" "\n  " out "  ${out}")
-  set(RunCMake_TEST_FAILED
-    "${RunCMake_TEST_FAILED}First install did not say 'Installing' as expected:\n${out}")
+  string(APPEND RunCMake_TEST_FAILED
+    "First install did not say 'Installing' as expected:\n${out}")
 endif()
 set(f ${RunCMake_TEST_BINARY_DIR}/prefix/dir/empty.txt)
 if(NOT EXISTS "${f}")
-  set(RunCMake_TEST_FAILED
-    "${RunCMake_TEST_FAILED}File was not installed:\n  ${f}\n")
+  string(APPEND RunCMake_TEST_FAILED
+    "File was not installed:\n  ${f}\n")
 endif()
 execute_process(COMMAND ${CMAKE_COMMAND} -P ${RunCMake_TEST_BINARY_DIR}/cmake_install.cmake
   OUTPUT_VARIABLE out ERROR_VARIABLE err)
 if(out MATCHES "(Installing|Up-to-date)")
   string(REGEX REPLACE "\n" "\n  " out "  ${out}")
-  set(RunCMake_TEST_FAILED
-    "${RunCMake_TEST_FAILED}Second install was not silent as expected:\n${out}")
+  string(APPEND RunCMake_TEST_FAILED
+    "Second install was not silent as expected:\n${out}")
 endif()
diff --git a/Tests/SimpleInstall/CMakeLists.txt b/Tests/SimpleInstall/CMakeLists.txt
index aee92f603..5a1392bb8 100644
--- a/Tests/SimpleInstall/CMakeLists.txt
+++ b/Tests/SimpleInstall/CMakeLists.txt
@@ -348,7 +348,7 @@ if(UNIX AND NOT APPLE)
   #    if(NOT SKIP_TZ)
   #      message("compress found and it was not a script")
   #      message("output from file command: [${output}]")
-  #      set(CPACK_GENERATOR "${CPACK_GENERATOR};TZ")
+  #      string(APPEND CPACK_GENERATOR ";TZ")
   #    else()
   #      message("compress found, but it was a script so dont use it")
   #      message("output from file command: [${output}]")
@@ -357,7 +357,7 @@ if(UNIX AND NOT APPLE)
   find_program(found_bz2
     NAMES bzip2)
   if(found_bz2)
-    set(CPACK_GENERATOR "${CPACK_GENERATOR};TBZ2")
+    string(APPEND CPACK_GENERATOR ";TBZ2")
   endif()
 endif()
 
diff --git a/Tests/SimpleInstallS2/CMakeLists.txt b/Tests/SimpleInstallS2/CMakeLists.txt
index aee92f603..5a1392bb8 100644
--- a/Tests/SimpleInstallS2/CMakeLists.txt
+++ b/Tests/SimpleInstallS2/CMakeLists.txt
@@ -348,7 +348,7 @@ if(UNIX AND NOT APPLE)
   #    if(NOT SKIP_TZ)
   #      message("compress found and it was not a script")
   #      message("output from file command: [${output}]")
-  #      set(CPACK_GENERATOR "${CPACK_GENERATOR};TZ")
+  #      string(APPEND CPACK_GENERATOR ";TZ")
   #    else()
   #      message("compress found, but it was a script so dont use it")
   #      message("output from file command: [${output}]")
@@ -357,7 +357,7 @@ if(UNIX AND NOT APPLE)
   find_program(found_bz2
     NAMES bzip2)
   if(found_bz2)
-    set(CPACK_GENERATOR "${CPACK_GENERATOR};TBZ2")
+    string(APPEND CPACK_GENERATOR ";TBZ2")
   endif()
 endif()
 
diff --git a/Tests/TryCompile/CMakeLists.txt b/Tests/TryCompile/CMakeLists.txt
index d11cfc50a..2f8e4fb3c 100644
--- a/Tests/TryCompile/CMakeLists.txt
+++ b/Tests/TryCompile/CMakeLists.txt
@@ -109,9 +109,9 @@ endif()
 # try to compile a file that should compile
 set(_c_flags "${CMAKE_C_FLAGS}")
 if(WATCOM)
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -dTESTDEF")
+  string(APPEND CMAKE_C_FLAGS " -dTESTDEF")
 else()
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} \"-DTESTDEF\"")
+  string(APPEND CMAKE_C_FLAGS " \"-DTESTDEF\"")
 endif()
 try_compile(SHOULD_PASS
     ${TryCompile_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp
diff --git a/Tests/VSMASM/CMakeLists.txt b/Tests/VSMASM/CMakeLists.txt
index f2570a309..2923e1527 100644
--- a/Tests/VSMASM/CMakeLists.txt
+++ b/Tests/VSMASM/CMakeLists.txt
@@ -4,7 +4,7 @@ if(CMAKE_SIZEOF_VOID_P EQUAL 8)
   add_definitions(-DTESTx64)
 else()
   add_definitions(-DTESTi386)
-  set(CMAKE_ASM_MASM_FLAGS "${CMAKE_ASM_MASM_FLAGS} /safeseh")
+  string(APPEND CMAKE_ASM_MASM_FLAGS " /safeseh")
 endif()
 include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
 add_executable(VSMASM main.c foo.asm)