diff --git a/js/src/js.msg b/js/src/js.msg
index 6793a221fd63..38dec12279b6 100644
--- a/js/src/js.msg
+++ b/js/src/js.msg
@@ -294,3 +294,4 @@ MSG_DEF(JSMSG_IN_AFTER_FOR_NAME,      211, 0, JSEXN_SYNTAXERR, "missing in after
 MSG_DEF(JSMSG_BAD_ITERATOR_RETURN,    212, 2, JSEXN_TYPEERR, "{0}.{1} returned a primitive value")
 MSG_DEF(JSMSG_KEYWORD_NOT_NS,         213, 0, JSEXN_SYNTAXERR, "keyword is used as namespace")
 MSG_DEF(JSMSG_BAD_GENERATOR_YIELD,    214, 1, JSEXN_TYPEERR, "yield from closing generator {0}")
+MSG_DEF(JSMSG_BAD_YIELD_SYNTAX,       215, 0, JSEXN_SYNTAXERR, "yield expression must be parenthesized")
diff --git a/js/src/jsparse.c b/js/src/jsparse.c
index 4aa90235d706..c560808a2fb1 100644
--- a/js/src/jsparse.c
+++ b/js/src/jsparse.c
@@ -3640,10 +3640,11 @@ Expr(JSContext *cx, JSTokenStream *ts, JSTreeContext *tc)
         pn = pn2;
         do {
 #if JS_HAS_GENERATORS
-            if (PN_LAST(pn)->pn_type == TOK_YIELD) {
-                js_ReportCompileErrorNumber(cx, ts,
-                                            JSREPORT_TS | JSREPORT_ERROR,
-                                            JSMSG_SYNTAX_ERROR);
+            pn2 = PN_LAST(pn);
+            if (pn2->pn_type == TOK_YIELD) {
+                js_ReportCompileErrorNumber(cx, pn2,
+                                            JSREPORT_PN | JSREPORT_ERROR,
+                                            JSMSG_BAD_YIELD_SYNTAX);
                 return NULL;
             }
 #endif
@@ -4121,6 +4122,14 @@ ArgumentList(JSContext *cx, JSTokenStream *ts, JSTreeContext *tc,
             JSParseNode *argNode = AssignExpr(cx, ts, tc);
             if (!argNode)
                 return JS_FALSE;
+#if JS_HAS_GENERATORS
+            if (argNode->pn_type == TOK_YIELD) {
+                js_ReportCompileErrorNumber(cx, argNode,
+                                            JSREPORT_PN | JSREPORT_ERROR,
+                                            JSMSG_BAD_YIELD_SYNTAX);
+                return NULL;
+            }
+#endif
             PN_APPEND(listNode, argNode);
         } while (js_MatchToken(cx, ts, TOK_COMMA));