diff --git a/Tests/ObjectLibrary/A/CMakeLists.txt b/Tests/ObjectLibrary/A/CMakeLists.txt
index e0a620e5c..121a8acba 100644
--- a/Tests/ObjectLibrary/A/CMakeLists.txt
+++ b/Tests/ObjectLibrary/A/CMakeLists.txt
@@ -1,10 +1,10 @@
 # Add -fPIC so objects can be used in shared libraries.
 # TODO: Need property for this.
-if(CMAKE_SHARED_LIBRARY_C_FLAGS)
+if(CMAKE_SHARED_LIBRARY_C_FLAGS AND NOT WATCOM)
   set(CMAKE_C_FLAGS "${CMAKE_SHARED_LIBRARY_C_FLAGS} ${CMAKE_C_FLAGS}")
 endif()
 
-add_definitions(-DA)
+add_definitions(-DA_DEF)
 
 add_custom_command(
   OUTPUT a1.c
diff --git a/Tests/ObjectLibrary/A/a.h b/Tests/ObjectLibrary/A/a.h
index 6bfbc82a0..7259f982e 100644
--- a/Tests/ObjectLibrary/A/a.h
+++ b/Tests/ObjectLibrary/A/a.h
@@ -1,6 +1,6 @@
-#ifndef A
-# error "A not defined"
+#ifndef A_DEF
+# error "A_DEF not defined"
 #endif
-#ifdef B
-# error "B must not be defined"
+#ifdef B_DEF
+# error "B_DEF must not be defined"
 #endif
diff --git a/Tests/ObjectLibrary/B/CMakeLists.txt b/Tests/ObjectLibrary/B/CMakeLists.txt
index 498d45df1..67172d132 100644
--- a/Tests/ObjectLibrary/B/CMakeLists.txt
+++ b/Tests/ObjectLibrary/B/CMakeLists.txt
@@ -5,11 +5,11 @@ endif()
 
 # Add -fPIC so objects can be used in shared libraries.
 # TODO: Need property for this.
-if(CMAKE_SHARED_LIBRARY_C_FLAGS)
+if(CMAKE_SHARED_LIBRARY_C_FLAGS AND NOT WATCOM)
   set(CMAKE_C_FLAGS "${CMAKE_SHARED_LIBRARY_C_FLAGS} ${CMAKE_C_FLAGS}")
 endif()
 
-add_definitions(-DB)
+add_definitions(-DB_DEF)
 add_library(B OBJECT b1.c b2.c)
 add_library(Bexport OBJECT b1${vs6}.c b2${vs6}.c)
 set_property(TARGET Bexport PROPERTY COMPILE_DEFINITIONS Bexport)
diff --git a/Tests/ObjectLibrary/B/b.h b/Tests/ObjectLibrary/B/b.h
index 632004dd9..11b22f427 100644
--- a/Tests/ObjectLibrary/B/b.h
+++ b/Tests/ObjectLibrary/B/b.h
@@ -1,8 +1,8 @@
-#ifdef A
-# error "A must not be defined"
+#ifdef A_DEF
+# error "A_DEF must not be defined"
 #endif
-#ifndef B
-# error "B not defined"
+#ifndef B_DEF
+# error "B_DEF not defined"
 #endif
 #if defined(_WIN32) && defined(Bexport)
 # define EXPORT_B __declspec(dllexport)