diff --git a/grudge/symbolic/mappers/__init__.py b/grudge/symbolic/mappers/__init__.py
index 3441852d0790a2d279b333e115340f7ccd9c1aad..2470bb863f122d354f7973adbf42deaa8df64e55 100644
--- a/grudge/symbolic/mappers/__init__.py
+++ b/grudge/symbolic/mappers/__init__.py
@@ -547,7 +547,8 @@ class GlobalToReferenceMapper(CSECachingMapperMixin, IdentityMapper):
         elif isinstance(expr.op, op.MInvSTOperator):
             return self.rec(
                     op.InverseMassOperator()(
-                        op.StiffnessTOperator(expr.op.xyz_axis)(expr.field)))
+                        op.StiffnessTOperator(expr.op.xyz_axis)(
+                            self.rec(expr.field))))
 
         else:
             return IdentityMapper.map_operator_binding(self, expr)