diff --git a/lib/scope.js b/lib/scope.js
index f08e771f..df0a7e00 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -79,9 +79,7 @@ SymbolDef.prototype = {
             if (!options.screw_ie8 && sym instanceof AST_SymbolLambda)
                 s = s.parent_scope;
             var def;
-            if (options.screw_ie8
-                && sym instanceof AST_SymbolCatch
-                && (def = this.defun.variables.get(this.name))) {
+            if (this.defun && (def = this.defun.variables.get(this.name))) {
                 this.mangled_name = def.mangled_name || def.name;
             } else
                 this.mangled_name = s.next_mangled(options, this);