diff --git a/Source/cmDefinitions.cxx b/Source/cmDefinitions.cxx
index 58500c94c8..d2b37bb4a0 100644
--- a/Source/cmDefinitions.cxx
+++ b/Source/cmDefinitions.cxx
@@ -49,16 +49,7 @@ const char* cmDefinitions::Get(const std::string& key)
 void cmDefinitions::Set(const std::string& key, const char* value)
 {
   Def def(value);
-  if(this->Up || def.Exists)
-    {
-    // In lower scopes we store keys, defined or not.
-    this->Map[key] = def;
-    }
-  else
-    {
-    // In the top-most scope we need not store undefined keys.
-    this->Map.erase(key);
-    }
+  this->Map[key] = def;
 }
 
 void cmDefinitions::Erase(const std::string& key)
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index d71b81517e..875442762a 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -78,7 +78,15 @@ public:
 
   void RemoveDefinition(std::string const& name)
   {
-    this->VarStack.top().Set(name, 0);
+    if (this->VarStack.size() > 1)
+      {
+      // In lower scopes we store keys, defined or not.
+      this->VarStack.top().Set(name, 0);
+      }
+    else
+      {
+      this->VarStack.top().Erase(name);
+      }
   }
 
   std::set<std::string> LocalKeys() const