diff --git a/programs/develop/cmm/main.cpp b/programs/develop/cmm/main.cpp
index 38188f7110..18db5edd12 100644
--- a/programs/develop/cmm/main.cpp
+++ b/programs/develop/cmm/main.cpp
@@ -1721,7 +1721,7 @@ FILE *CreateOutPut(char *ext,char *mode)
 {
 char buf[256];
 FILE *diskout;
-    if(!ext && strlen(ext)) {
+    if(ext && strlen(ext)) {
         sprintf(buf,"%s.%s",rawfilename,ext);
     } else {
         strcpy(buf, rawfilename);