diff --git a/js/src/frontend/Parser.cpp b/js/src/frontend/Parser.cpp
index 1be57f8f5b..ec4a975e64 100644
--- a/js/src/frontend/Parser.cpp
+++ b/js/src/frontend/Parser.cpp
@@ -9820,7 +9820,6 @@ Parser<ParseHandler>::primaryExpr(YieldHandling yieldHandling, TripledotHandling
         if (!expr)
             return null();
         MUST_MATCH_TOKEN(TOK_RP, JSMSG_PAREN_IN_PAREN);
-        handler.setEndPosition(expr, pos().end);
         return handler.parenthesize(expr);
       }
 
diff --git a/js/src/tests/ecma_6/Class/parenExprToString.js b/js/src/tests/ecma_6/Class/parenExprToString.js
new file mode 100644
index 0000000000..a93972ce92
--- /dev/null
+++ b/js/src/tests/ecma_6/Class/parenExprToString.js
@@ -0,0 +1,8 @@
+// Test that parenthesized class expressions don't get their toString offsets
+// messed up.
+
+assertEq((class {}).toString(), "class {}");
+assertEq(((class {})).toString(), "class {}");
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0, "OK");