diff --git a/flask_cache/__init__.py b/flask_cache/__init__.py
index 85d90e3..0ecdbc0 100644
--- a/flask_cache/__init__.py
+++ b/flask_cache/__init__.py
@@ -347,6 +347,9 @@ def _memoize_version(self, f, args=None,
             self.cache.delete_many(fetch_keys[-1])
             return fname, None
 
+        # Mangle keys before using in the backend
+        fetch_keys = list(map(lambda k: hashlib.md5(k.encode()).hexdigest(), fetch_keys))
+
         version_data_list = list(self.cache.get_many(*fetch_keys))
         dirty = False