diff --git a/memoize/__init__.py b/memoize/__init__.py
index 5a1d03d..d2e2635 100644
--- a/memoize/__init__.py
+++ b/memoize/__init__.py
@@ -350,7 +350,7 @@ def decorated_function(*args, **kwargs):
                     )
                     return f(*args, **kwargs)
 
-                if rv == self.default_cache_value:
+                if rv is self.default_cache_value:
                     rv = f(*args, **kwargs)
                     try:
                         self.set(