diff --git a/src/sage/modules/with_basis/morphism.py b/src/sage/modules/with_basis/morphism.py
index 2efcc4f25e9..b8fe98111b2 100644
--- a/src/sage/modules/with_basis/morphism.py
+++ b/src/sage/modules/with_basis/morphism.py
@@ -404,10 +404,10 @@ def __call__(self, *args):
         if self._is_module_with_basis_over_same_base_ring:
             return self.codomain().linear_combination(
                     (self._on_basis(*(before+(index,)+after)), coeff )
-                    for (index, coeff) in mc.items() if self._on_basis(index))
+                    for (index, coeff) in mc.items())
         else:
             return sum((coeff * self._on_basis(*(before+(index,)+after))
-                       for (index, coeff) in mc.items() if self._on_basis(index)), self._zero)
+                       for (index, coeff) in mc.items()), self._zero)
 
     # As per the specs of Map, we should in fact implement _call_.
     # However we currently need to abuse Map.__call__ (which strict