diff --git a/pymbolic/mapper/__init__.py b/pymbolic/mapper/__init__.py
index 700d4017940e72276d602d134f8e32ca86f41b1a..eddea8de75a0df9adf2bda553fd3563117691775 100644
--- a/pymbolic/mapper/__init__.py
+++ b/pymbolic/mapper/__init__.py
@@ -633,8 +633,8 @@ class IdentityMapper(Mapper):
     def map_substitution(self, expr, *args, **kwargs):
         child = self.rec(expr.child, *args, **kwargs)
         values = tuple([self.rec(v, *args, **kwargs) for v in expr.values])
-        if child is expr.child and all([val is orig_val
-                for val, orig_val in zip(values, expr.values)]):
+        if child is expr.child and all(val is orig_val
+                for val, orig_val in zip(values, expr.values)):
             return expr
 
         return type(expr)(child, expr.variables, values)