diff --git a/devito/types/basic.py b/devito/types/basic.py
index 4b0ea425c4..e70a105296 100644
--- a/devito/types/basic.py
+++ b/devito/types/basic.py
@@ -877,7 +877,7 @@ def __new__(cls, *args, **kwargs):
         name = kwargs.get('name')
         alias = kwargs.get('alias')
         function = kwargs.get('function')
-        if alias or (function and function.name != name):
+        if alias is True or (function and function.name != name):
             function = kwargs['function'] = None
 
         # If same name/indices and `function` isn't None, then it's