1 files changed, 4 insertions, 6 deletions
diff --git a/lib/compress.js b/lib/compress.js
index 8cf7262a..93dbe063 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1350,7 +1350,7 @@ merge(Compressor.prototype, {
                     var lhs = get_lhs(candidate);
                     var side_effects = lhs && lhs.has_side_effects(compressor);
                     var scan_lhs = lhs && !side_effects && !is_lhs_read_only(lhs, compressor);
-                    var scan_rhs = foldable(get_rhs(candidate));
+                    var scan_rhs = foldable(candidate);
                     if (!scan_lhs && !scan_rhs) continue;
                     var modify_toplevel = false;
                     // Locate symbols which may execute code outside of scanning range
@@ -1841,10 +1841,6 @@ merge(Compressor.prototype, {
                 }
             }
 
-            function get_rhs(expr) {
-                return candidate instanceof AST_Assign && candidate.operator == "=" && candidate.right;
-            }
-
             function invariant(expr) {
                 if (expr instanceof AST_Array) return false;
                 if (expr instanceof AST_Binary && lazy_op[expr.operator]) {
@@ -1859,7 +1855,9 @@ merge(Compressor.prototype, {
             }
 
             function foldable(expr) {
-                if (!expr) return false;
+                while (expr instanceof AST_Assign && expr.operator == "=") {
+                    expr = expr.right;
+                }
                 if (expr instanceof AST_SymbolRef) {
                     var value = expr.evaluate(compressor);
                     if (value === expr) return rhs_exact_match;