diff --git a/parser.js b/parser.js
index 11c55a2..2e65701 100644
--- a/parser.js
+++ b/parser.js
@@ -918,7 +918,7 @@
     }
 
     function bailOctalEscapeIfUnicode(from, pos) {
-      if (hasUnicodeFlag) {
+      if (hasUnicodeFlag || hasUnicodeSetFlag) {
         bail("Invalid decimal escape in unicode mode", null, from, pos);
       }
     }
diff --git a/test/test-data-unicode-set.json b/test/test-data-unicode-set.json
index c3735f8..dfcb83e 100644
--- a/test/test-data-unicode-set.json
+++ b/test/test-data-unicode-set.json
@@ -1493,5 +1493,11 @@
       9
     ],
     "raw": "[^\\q{AB}]"
+  },
+  "\\1": {
+    "type": "error",
+    "name": "SyntaxError",
+    "message": "Invalid decimal escape in unicode mode at position 1\n    \\1\n     ^",
+    "input": "\\1"
   }
 }