diff --git a/lib/compress.js b/lib/compress.js
index 70fd03a8..cc691c43 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -750,7 +750,7 @@ merge(Compressor.prototype, {
                             || node instanceof AST_SymbolRef
                                && (lvalues && lvalues[node.name]
                                    || side_effects && !references_in_scope(node.definition()))
-                            || lvalues && (sym = is_lhs(node.left, node)) && get_symbol(sym).name in lvalues
+                            || lvalues && (sym = lhs_or_def(node)) && get_symbol(sym).name in lvalues
                             || parent instanceof AST_Binary
                                 && (parent.operator == "&&" || parent.operator == "||")
                             || parent instanceof AST_Case
@@ -828,6 +828,11 @@ merge(Compressor.prototype, {
                 return lvalues;
             }
 
+            function lhs_or_def(node) {
+                if (node instanceof AST_VarDef) return node.value && node.name;
+                return is_lhs(node.left, node);
+            }
+
             function remove_candidate(expr) {
                 var found = false;
                 return statements[stat_index].transform(new TreeTransformer(function(node, descend, in_list) {
diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index cbaa91ff..bbc9c65b 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -2146,3 +2146,24 @@ issue_315: {
     }
     expect_stdout: true
 }
+
+lvalues_def: {
+    options = {
+        collapse_vars: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var a = 0, b = 1;
+        var a = b++, b = +function() {}();
+        a && a[a++];
+        console.log(a, b);
+    }
+    expect: {
+        var a = 0, b = 1;
+        var a = b++, b = +void 0;
+        a && a[a++];
+        console.log(a, b);
+    }
+    expect_stdout: true
+}