diff --git a/CHANGELOG.md b/CHANGELOG.md
index b5a09c7..2a258d7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 > **Note**: odd version numbers, for example, `0.13.0`, are not included in this changelog. They are used to test the new features and fixes before the final release.
 
-## [0.22.0] - 2025-05-01
+## [0.22.1] - 2025-05-02
 
 ### Added:
 
@@ -20,6 +20,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Snippets: Updated all snippets to use `v0.27.0` schema
 
+### Fixed:
+
+- Command: Using `dev-proxy-toolkit.start` would throw an error when active file is not a Dev Proxy config file
+
 ## [0.20.0] - 2025-04-01
 
 ### Added:
diff --git a/package-lock.json b/package-lock.json
index 1a45570..d986784 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "dev-proxy-toolkit",
-  "version": "0.22.0",
+  "version": "0.22.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "dev-proxy-toolkit",
-      "version": "0.22.0",
+      "version": "0.22.1",
       "dependencies": {
         "json-to-ast": "^2.1.0"
       },
diff --git a/package.json b/package.json
index af73fda..cfbb771 100644
--- a/package.json
+++ b/package.json
@@ -2,7 +2,7 @@
   "name": "dev-proxy-toolkit",
   "displayName": "Dev Proxy Toolkit",
   "description": "Makes it easy to create and update Dev Proxy configuration files.",
-  "version": "0.22.0",
+  "version": "0.22.1",
   "publisher": "garrytrinder",
   "engines": {
     "vscode": "^1.89.0"
diff --git a/src/helpers.ts b/src/helpers.ts
index a186b7e..59fd632 100644
--- a/src/helpers.ts
+++ b/src/helpers.ts
@@ -47,6 +47,11 @@ export const getStartPositionFromASTNode = (
 export const isConfigFile = (document: vscode.TextDocument) => {
   let isConfigFile = false;
 
+  const fileName = document.fileName.toLowerCase();
+  if (!(fileName.endsWith('.json') || fileName.endsWith('.jsonc'))) {
+    return false;
+  }
+
   const documentNode = parse(document.getText()) as parse.ObjectNode;
 
   // we know that its a config file if