diff --git a/Source/build.cpp b/Source/build.cpp
index 36fff032..d24d5537 100644
--- a/Source/build.cpp
+++ b/Source/build.cpp
@@ -539,7 +539,10 @@ int CEXEBuild::preprocess_string(char *out, const char *in)
 
             while ( pUserVarName > p )
             {
+                char b = ((char*)p)[pUserVarName-p];
+                ((char*)p)[pUserVarName-p] = 0;
                 int idxUserVar = m_UserVarNames.get((char*)p, pUserVarName-p);
+                ((char*)p)[pUserVarName-p] = b;
                 if ( idxUserVar >= 0 )
                 {
                   // Well, using variables inside string formating doens't mean