diff --git a/BaseTools/Source/Python/Common/Misc.py b/BaseTools/Source/Python/Common/Misc.py
index 714eb840ea..a488536cb4 100755
--- a/BaseTools/Source/Python/Common/Misc.py
+++ b/BaseTools/Source/Python/Common/Misc.py
@@ -536,7 +536,8 @@ def CopyFileOnChange(SrcFile, Dst, FileLock=None):
     SrcFile = LongFilePath(SrcFile)
     Dst = LongFilePath(Dst)
 
-    if not os.path.exists(SrcFile):
+    if os.path.isdir(SrcFile):
+        EdkLogger.error(None, FILE_COPY_FAILURE, ExtraData='CopyFileOnChange SrcFile is a dir, not a file: %s' % SrcFile)
         return False
 
     if os.path.isdir(Dst):