diff --git a/src/controllers/ImageController.ts b/src/controllers/ImageController.ts
index 58c2a92..5e1fcac 100644
--- a/src/controllers/ImageController.ts
+++ b/src/controllers/ImageController.ts
@@ -1,5 +1,6 @@
 import { Request, Response } from "express";
 import imageService from "../services/ImageService";
+import mongoose, { mongo } from "mongoose";
 
 class ImageController {
     async getAllImages(req: Request, res: Response): Promise<void> {
@@ -20,12 +21,16 @@ class ImageController {
             const image = await imageService.add(req.body);
             res.status(201).json({ image });
         } catch (error: any) {
-            if (error.code === 11000) {
+            if (error instanceof mongo.MongoServerError && error.code === 11000) {
                 // Should return 409 Conflict for existing urls
-                res.status(409).json({ error: "Existing URL" });
+                res.status(409).json({ error: `the image with URL ${error.keyValue.url} already exists` });
+            } else if (error instanceof mongoose.Error.ValidationError) {
+                // Should return 400 Bad request for invalid requests
+                res.status(400).json({ error: error.message });
+            } else {
+                // Return 500 in other case
+                res.status(500).json({ error: error });
             }
-            // Should return 400 Bad request for invalid requests
-            res.status(400).json({ error: error });
         }
     }
 }
diff --git a/src/services/ImageService.ts b/src/services/ImageService.ts
index c8a3c16..bfaab2f 100644
--- a/src/services/ImageService.ts
+++ b/src/services/ImageService.ts
@@ -1,12 +1,12 @@
-import ImageModel, { Image } from "../models/ImageModel";
+import imageModel, { Image } from "../models/ImageModel";
 
 class ImageService {
     async findAll(): Promise<Image[]> {
-        const allImages = await ImageModel.find();
+        const allImages = await imageModel.find();
         return allImages;
     }
     async add(image: Image): Promise<Image> {
-        const newImage = await ImageModel.create(image);
+        const newImage = await imageModel.create(image);
         return newImage;
     }
 }
diff --git a/tests/app.test.ts b/tests/app.test.ts
index f8ec9f4..455b873 100644
--- a/tests/app.test.ts
+++ b/tests/app.test.ts
@@ -1,6 +1,14 @@
-import { describe, expect, it, mock } from "bun:test";
+import { afterEach, describe, expect, it, mock } from "bun:test";
 import request from "supertest";
 import { app } from "../src";
+import imageService from "../src/services/ImageService";
+
+const imageServiceOriginal = imageService;
+
+afterEach(() => {
+    mock.restore();
+    mock.module("../src/services/ImageService", () => ({ default: imageServiceOriginal }));
+})
 
 describe("GET / shows all of the endpoints", async () => {
     const res = await request(app).get("/");
@@ -49,15 +57,32 @@ describe("POST /images works properly", () => {
             tags: ["2girls", "touhou"]
         });
 
-        expect(res.status).toSatisfy(status => [409].includes(status));
+        expect(res.status).toBe(409);
+    });
+
+    it("should return 500 for an error on the service", async () => {
+        mock.module("../src/services/ImageService", () => ({
+            default: {
+                add: () => { throw new Error("This is an expected testing error"); }
+            }
+        }));
+
+        const res = await request(app).post("/images").send({
+            url: "https://test.url.com/3",
+            status: "available",
+            tags: ["2girls", "touhou"]
+        });
+        
+        expect(res.status).toBe(500);
     });
 
     it("should return 400 for malformed requests", async () => {
+        mock.restore();
         const res = await request(app).post("/images").send({
-            url: "https://test.url.com/3",
+            url: "https://test.url.com/4",
             status: "wrong",
             tags: ["2girls", "touhou"]
         });
-        expect(res.status).toSatisfy(status => [400].includes(status));
+        expect(res.status).toBe(400);
     });
 });
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