diff --git a/src/oauth2client/_helpers.py b/src/oauth2client/_helpers.py
index e9123971..d9cda749 100644
--- a/src/oauth2client/_helpers.py
+++ b/src/oauth2client/_helpers.py
@@ -251,8 +251,8 @@ def validate_file(filename):
         raise IOError(_SYM_LINK_MESSAGE.format(filename))
     elif os.path.isdir(filename):
         raise IOError(_IS_DIR_MESSAGE.format(filename))
-    elif not os.path.isfile(filename):
-        warnings.warn(_MISSING_FILE_MESSAGE.format(filename))
+    #elif not os.path.isfile(filename):
+    #    warnings.warn(_MISSING_FILE_MESSAGE.format(filename))
 
 
 def _parse_pem_key(raw_key_input):