diff --git a/Source/cmake.cxx b/Source/cmake.cxx
index 90828373a1..491a2987bf 100644
--- a/Source/cmake.cxx
+++ b/Source/cmake.cxx
@@ -290,7 +290,7 @@ bool cmake::SetCacheArgs(const std::vector<std::string>& args)
           }
         else
           {
-          cmSystemTools::Error("-D  must be followed with VAR=VALUE.");
+          cmSystemTools::Error("-D must be followed with VAR=VALUE.");
           return false;
           }
         }