diff --git a/grudge/symbolic/mappers/__init__.py b/grudge/symbolic/mappers/__init__.py
index 64d26c38fc49d919802e1d4b3bd603435acf4d50..76864e7d1b4ae389ea3fc20e69e7d520908555eb 100644
--- a/grudge/symbolic/mappers/__init__.py
+++ b/grudge/symbolic/mappers/__init__.py
@@ -1294,7 +1294,7 @@ class SymbolicEvaluator(pymbolic.mapper.evaluator.EvaluationMapper):
                     )
 
     def map_common_subexpression(self, expr):
-        return type(expr)(expr.child, expr.prefix, expr.scope)
+        return type(expr)(self.rec(expr.child), expr.prefix, expr.scope)
 
 # }}}