diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 6d09bb7b1..4f836e279 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1242,7 +1242,7 @@ void EvalState::createBaseEnv()
        language feature gets added.  It's not necessary to increase it
        when primops get added, because you can just use `builtins ?
        primOp' to check. */
-    mkInt(v, 1);
+    mkInt(v, 2);
     addConstant("__langVersion", v);
 
     // Miscellaneous