diff --git a/util/upload-cfn-templates.py b/util/upload-cfn-templates.py
index f50b499c6a..81cfacd137 100644
--- a/util/upload-cfn-templates.py
+++ b/util/upload-cfn-templates.py
@@ -32,8 +32,8 @@ def get_template_extension(templates_dir, template_name):
             "Found 0 or multiple matching files for template name {}: {}".format(template_name, matching_files)
         )
     file_name = os.path.basename(matching_files[0])
-    extension = os.path.splitext(file_name)[1]
-    if extension not in {".cfn.json", ".cfn.yaml"}:
+    extension = file_name.split(".cfn.")[-1]
+    if extension not in {"json", "yaml"}:
         raise Exception("Found invalid extension for template {}: {}".format(template_name, extension))
     return extension