diff --git a/src/tests/kernel/metavar.cpp b/src/tests/kernel/metavar.cpp
index 8a2415098..3c6ccc4f3 100644
--- a/src/tests/kernel/metavar.cpp
+++ b/src/tests/kernel/metavar.cpp
@@ -46,14 +46,13 @@ void display_assumptions(std::ostream & out, justification const & j) {
 }
 
 static std::ostream & operator<<(std::ostream & out, substitution const & s) {
-    // bool first = true;
-    // s.for_each([&](name const & n, expr const & v, justification const & j) {
-    //         if (first) first = false; else out << "\n";
-    //         out << "?" << n << " <- " << v << " {";
-    //         display_assumptions(out, j);
-    //         out << "}";
-    //     });
-    s.for_each_expr([](name const &, expr const &, justification const &) {});
+    bool first = true;
+    s.for_each_expr([&](name const & n, expr const & v, justification const & j) {
+            if (first) first = false; else out << "\n";
+            out << "?" << n << " <- " << v << " {";
+            display_assumptions(out, j);
+            out << "}";
+        });
     return out;
 }