diff --git a/Source/cmOptionCommand.cxx b/Source/cmOptionCommand.cxx
index 5bd66a518..b4e57a157 100644
--- a/Source/cmOptionCommand.cxx
+++ b/Source/cmOptionCommand.cxx
@@ -70,7 +70,8 @@ bool cmOptionCommand
     {
     initialValue = args[2];
     }
-  this->Makefile->AddCacheDefinition(args[0].c_str(), initialValue.c_str(),
+  bool init = cmSystemTools::IsOn(initialValue.c_str());
+  this->Makefile->AddCacheDefinition(args[0].c_str(), init? "ON":"OFF",
                                      args[1].c_str(), cmCacheManager::BOOL);
   return true;
 }