diff --git a/BaseTools/Source/C/GenVtf/GenVtf.c b/BaseTools/Source/C/GenVtf/GenVtf.c
index ff0e7cfb2c..2ae9a7be2c 100644
--- a/BaseTools/Source/C/GenVtf/GenVtf.c
+++ b/BaseTools/Source/C/GenVtf/GenVtf.c
@@ -2703,10 +2703,12 @@ Returns:
     }
     SymFileName = VTF_SYM_FILE;
   } else {
-    assert (OutFileName1);
-    INTN OutFileNameLen = strlen(OutFileName1);
+    INTN OutFileNameLen;
     INTN NewIndex;
 
+    assert (OutFileName1);
+    OutFileNameLen = strlen(OutFileName1);
+
     for (NewIndex = OutFileNameLen; NewIndex > 0; --NewIndex) {
       if (OutFileName1[NewIndex] == '/' || OutFileName1[NewIndex] == '\\') {
         break;