diff --git a/dist/templateManager.user.js b/dist/templateManager.user.js
index 378559b..1f5fc2d 100644
--- a/dist/templateManager.user.js
+++ b/dist/templateManager.user.js
@@ -847,6 +847,15 @@
         getCacheBustString() {
             return Math.floor(Date.now() / CACHE_BUST_PERIOD).toString(36);
         }
+        validateJSON(str) {
+            try {
+                JSON.parse(str);
+                return true;
+            }
+            catch (_a) {
+                return false;
+            }
+        }
         loadTemplatesFromJsonURL(url, minPriority = 0, lastContact = '') {
             let _url = new URL(url);
             let uniqueString = `${_url.origin}${_url.pathname}`;
@@ -870,6 +879,10 @@
                         this.responseDiffs.push(responseTime - Date.now());
                     }
                     // parse the response
+                    if (this.validateJSON(response.responseText) === false) {
+                        console.error(`Invalid JSON from ${_url}`);
+                        return;
+                    }
                     let json = JSON.parse(response.responseText);
                     // read blacklist. These will never be loaded
                     if (json.blacklist) {
diff --git a/package-lock.json b/package-lock.json
index c310a93..475cf06 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "template-manager",
-  "version": "0.6.2",
+  "version": "0.6.4",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "template-manager",
-      "version": "0.6.2",
+      "version": "0.6.4",
       "license": "MIT",
       "dependencies": {
         "@types/greasemonkey": "^4.0.4"
diff --git a/src/templateManager.ts b/src/templateManager.ts
index f4a3067..560023f 100644
--- a/src/templateManager.ts
+++ b/src/templateManager.ts
@@ -115,6 +115,15 @@ export class TemplateManager {
         return Math.floor(Date.now() / CACHE_BUST_PERIOD).toString(36)
     }
 
+    validateJSON(str: string) {
+        try {
+            JSON.parse(str);
+            return true;
+        } catch {
+            return false;
+        }
+    }
+
     loadTemplatesFromJsonURL(url: string | URL, minPriority = 0, lastContact = '') {
         let _url = new URL(url);
         let uniqueString = `${_url.origin}${_url.pathname}`;
@@ -141,6 +150,10 @@ export class TemplateManager {
                     this.responseDiffs.push(responseTime - Date.now());
                 }
                 // parse the response
+                if (this.validateJSON(response.responseText) === false) {
+                    console.error(`Invalid JSON from ${_url}`);
+                    return;
+                }
                 let json: JsonParams = JSON.parse(response.responseText);
                 // read blacklist. These will never be loaded
                 if (json.blacklist) {