diff --git a/Source/cmSetCommand.cxx b/Source/cmSetCommand.cxx
index 20f38be10..bb193bf9f 100644
--- a/Source/cmSetCommand.cxx
+++ b/Source/cmSetCommand.cxx
@@ -62,9 +62,17 @@ bool cmSetCommand
     this->Makefile->RemoveDefinition(args[0].c_str());
     return true;
     }
+  // SET (VAR PARENT_SCOPE) // Removes the definition of VAR
+                            // in the parent scope.
+  else if (args.size() == 2 && args[args.size()-1] == "PARENT_SCOPE")
+    {
+    this->Makefile->RaiseScope(variable, 0);
+    return true;
+    }
 
   // here are the remaining options
   //  SET (VAR value )
+  //  SET (VAR value PARENT_SCOPE)
   //  SET (VAR CACHE TYPE "doc String" [FORCE])
   //  SET (VAR value CACHE TYPE "doc string" [FORCE])
   std::string value;  // optional
@@ -114,15 +122,8 @@ bool cmSetCommand
 
   if (parentScope)
     {
-    if (value.empty())
-      {
-      this->Makefile->RaiseScope(variable, 0);
-      }
-    else
-      {
-      this->Makefile->RaiseScope(variable, value.c_str());
-      }
-      return true;
+    this->Makefile->RaiseScope(variable, value.c_str());
+    return true;
     }
 
 
diff --git a/Tests/RunCMake/CMakeLists.txt b/Tests/RunCMake/CMakeLists.txt
index bf3dcc143..bb1b90953 100644
--- a/Tests/RunCMake/CMakeLists.txt
+++ b/Tests/RunCMake/CMakeLists.txt
@@ -107,6 +107,7 @@ add_RunCMake_test(list)
 add_RunCMake_test(message)
 add_RunCMake_test(string)
 add_RunCMake_test(try_compile)
+add_RunCMake_test(set)
 add_RunCMake_test(variable_watch)
 add_RunCMake_test(CMP0004)
 add_RunCMake_test(TargetPolicies)
diff --git a/Tests/RunCMake/set/CMakeLists.txt b/Tests/RunCMake/set/CMakeLists.txt
new file mode 100644
index 000000000..4b3de84d9
--- /dev/null
+++ b/Tests/RunCMake/set/CMakeLists.txt
@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 2.8.12)
+project(${RunCMake_TEST} NONE)
+include(${RunCMake_TEST}.cmake)
diff --git a/Tests/RunCMake/set/PARENT_SCOPE-result.txt b/Tests/RunCMake/set/PARENT_SCOPE-result.txt
new file mode 100644
index 000000000..573541ac9
--- /dev/null
+++ b/Tests/RunCMake/set/PARENT_SCOPE-result.txt
@@ -0,0 +1 @@
+0
diff --git a/Tests/RunCMake/set/PARENT_SCOPE.cmake b/Tests/RunCMake/set/PARENT_SCOPE.cmake
new file mode 100644
index 000000000..9bd6bcace
--- /dev/null
+++ b/Tests/RunCMake/set/PARENT_SCOPE.cmake
@@ -0,0 +1,33 @@
+set(FOO )
+set(BAR "bar")
+set(BAZ "baz")
+set(BOO "boo")
+
+function(_parent_scope)
+    set(FOO "foo" PARENT_SCOPE)
+    set(BAR "" PARENT_SCOPE)
+    set(BAZ PARENT_SCOPE)
+    unset(BOO PARENT_SCOPE)
+endfunction()
+
+_parent_scope()
+
+if(NOT DEFINED FOO)
+  message(FATAL_ERROR "FOO not defined")
+elseif(NOT "${FOO}" STREQUAL "foo")
+  message(FATAL_ERROR "FOO should be \"foo\", not \"${FOO}\"")
+endif()
+
+if(NOT DEFINED BAR)
+  message(FATAL_ERROR "BAR not defined")
+elseif(NOT "${BAR}" STREQUAL "")
+  message(FATAL_ERROR "BAR should be an empty string, not \"${BAR}\"")
+endif()
+
+if(DEFINED BAZ)
+  message(FATAL_ERROR "BAZ defined")
+endif()
+
+if(DEFINED BOO)
+  message(FATAL_ERROR "BOO defined")
+endif()
diff --git a/Tests/RunCMake/set/RunCMakeTest.cmake b/Tests/RunCMake/set/RunCMakeTest.cmake
new file mode 100644
index 000000000..5d036e3b8
--- /dev/null
+++ b/Tests/RunCMake/set/RunCMakeTest.cmake
@@ -0,0 +1,3 @@
+include(RunCMake)
+
+run_cmake(PARENT_SCOPE)