--- a/js/src/jsfun.cpp
+++ b/js/src/jsfun.cpp
@@ -1538,18 +1538,18 @@ UnescapeSubstr(TextChar* text, size_t st
                     code = JS7_UNHEX(text[i + 1]);
                     code = (code << 4) + JS7_UNHEX(text[i + 2]);
                     code = (code << 4) + JS7_UNHEX(text[i + 3]);
                     code = (code << 4) + JS7_UNHEX(text[i + 4]);
                     i += 4;
                     if (code < 0x10000) {
                         status = buf.append((char16_t)code);
                     } else {
-                        status = status && buf.append((char16_t)((code - 0x10000) / 1024 + 0xD800));
-                        status = status && buf.append((char16_t)(((code - 0x10000) % 1024) + 0xDC00));
+                        status = buf.append((char16_t)((code - 0x10000) / 1024 + 0xD800)) &&
+                            buf.append((char16_t)(((code - 0x10000) % 1024) + 0xDC00));
                     }
                     break;
                 }
             }
             if (!status)
                 return false;
         } else {
             if (!buf.append(text[i]))