diff --git a/.circleci/config.yml b/.circleci/config.yml
index d405486b5..00cbdf5bc 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -82,6 +82,9 @@ jobs:
       - run:
           name: Test - Coverage
           command: npm run test:coverage
+      - run:
+          name: Test - Content Negotiation
+          command: npm run test:content-negotiation
 
 workflows:
   build_and_test:
diff --git a/package.json b/package.json
index 31859cce1..16277d5d0 100644
--- a/package.json
+++ b/package.json
@@ -27,6 +27,7 @@
     "test:api-unit:themes": "jest \"server/.*.spec.js\" -t \"theme bundle\" --verbose",
     "test:api-unit:css": "jest \"server/.*.spec.js\" -t \"Get CSS\" --verbose",
     "test:api-unit:notifications": "jest \"server/.*.spec.js\" -t \"Notifications\" --verbose",
+    "test:content-negotiation": "jest \"server/middleware/.*.spec.js\" --verbose",
     "test:coverage": "jest --coverage --silent --runInBand",
     "test:dev": "jest --verbose --watch",
     "test:basic": "jest tests/markdown/basic.test.js --verbose",
diff --git a/server/middleware/content-negotiation.js b/server/middleware/content-negotiation.js
index ece60e064..9625a5826 100644
--- a/server/middleware/content-negotiation.js
+++ b/server/middleware/content-negotiation.js
@@ -6,7 +6,7 @@ export default (req, res, next)=>{
 	const isImageRequest = req.get('Accept')?.split(',')
         ?.filter((h)=>!h.includes('q='))
         ?.every((h)=>/image\/.*/.test(h));
-	if(isImageRequest && !isLocalEnvironment && !req.url?.startsWith('/staticImages')) {
+	if(isImageRequest && !(isLocalEnvironment && req.url?.startsWith('/staticImages'))) {
 		return res.status(406).send({
 			message : 'Request for image at this URL is not supported'
 		});
diff --git a/server/middleware/content-negotiation.spec.js b/server/middleware/content-negotiation.spec.js
new file mode 100644
index 000000000..80b9e515d
--- /dev/null
+++ b/server/middleware/content-negotiation.spec.js
@@ -0,0 +1,41 @@
+import contentNegotiationMiddleware from './content-negotiation.js';
+
+describe('content-negotiation-middleware', ()=>{
+	let request;
+	let response;
+	let next;
+
+	beforeEach(()=>{
+		request = {
+			get : function(key) {
+				return this[key];
+			}
+		};
+		response = {
+			status : jest.fn(()=>response),
+			send   : jest.fn(()=>{})
+		};
+		next = jest.fn();
+	});
+
+	it('should return 406 on image request', ()=>{
+		contentNegotiationMiddleware({
+			Accept : 'image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8',
+			...request
+		}, response);
+
+		expect(response.status).toHaveBeenLastCalledWith(406);
+		expect(response.send).toHaveBeenCalledWith({
+			message : 'Request for image at this URL is not supported'
+		});
+	});
+
+	it('should call next on non-image request', ()=>{
+		contentNegotiationMiddleware({
+			Accept : 'text,image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8',
+			...request
+		}, response, next);
+
+		expect(next).toHaveBeenCalled();
+	});
+});