diff --git a/CHANGELOG.md b/CHANGELOG.md
index c73e46e..0be1526 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [v3.5.1] - 2020-03-16
+### Fixed
+- Support insta-checking for legacy puzzles
+
 ## [v3.5.0] - 2020-03-13
 ### Changed
 - We are now using SHA256 instead of djb2hash
diff --git a/VERSION b/VERSION
index 1545d96..d5c0c99 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-3.5.0
+3.5.1
diff --git a/theme/puzzle.js b/theme/puzzle.js
index 2c084c6..a9b8cdb 100644
--- a/theme/puzzle.js
+++ b/theme/puzzle.js
@@ -84,11 +84,11 @@ async function possiblyCorrect(answer) {
       return answer
     }
     for (let end = 0; end <= answer.length; end += 1) {
-      if (window.puzzle.xAnchors.includes("end") && (end != answer.length)) {
+      if (window.puzzle.xAnchors && window.puzzle.xAnchors.includes("end") && (end != answer.length)) {
         continue
       }
       for (let beg = 0; beg < answer.length; beg += 1) {
-        if (window.puzzle.xAnchors.includes("begin") && (beg != 0)) {
+        if (window.puzzle.xAnchors && window.puzzle.xAnchors.includes("begin") && (beg != 0)) {
           continue
         }
         let sub = answer.substring(beg, end)
@@ -266,4 +266,3 @@ if (document.readyState === "loading") {
 } else {
   init()
 }
-