diff --git a/programs/develop/webpack/plugin-extension/feature-web-resources/__spec__/index.spec.ts b/programs/develop/webpack/plugin-extension/feature-web-resources/__spec__/index.spec.ts
new file mode 100644
index 00000000..6c5fc0f7
--- /dev/null
+++ b/programs/develop/webpack/plugin-extension/feature-web-resources/__spec__/index.spec.ts
@@ -0,0 +1,199 @@
+import { Asset, Compilation } from "webpack";
+import { WebResourcesPlugin } from ".."
+
+type Manifest = Partial<chrome.runtime.ManifestV2> | Partial<chrome.runtime.ManifestV3>;
+
+describe('generateManifestPatches', () => {
+  const plugin = new WebResourcesPlugin({
+    manifestPath: 'manifest.json',
+  });
+
+  function runWith(entryImports: Record<string, string[]>, partialManifest: Manifest = {}) {
+    const manifest = {
+      ...partialManifest,
+    };
+
+    const manifestSource = {
+      source: () => JSON.stringify(manifest)
+    } as Asset['source'];
+    const manifestAsset = {
+      name: 'manifest.json',
+      source: manifestSource,
+    } as unknown as Readonly<Asset>;
+
+    const updateAssetMock = jest.fn<void, [string, Asset['source']]>();
+
+    plugin['generateManifestPatches'](
+      {
+        getAsset: () => manifestAsset,
+        assets: {
+          'manifest.json': manifestSource,
+        },
+        updateAsset: updateAssetMock,
+      } as unknown as Compilation,
+      entryImports
+    );
+
+    expect(updateAssetMock).toHaveBeenCalledTimes(1);
+    const callArgs = updateAssetMock.mock.calls[0];
+    expect(callArgs[0]).toEqual('manifest.json');
+    return JSON.parse(callArgs[1].source().toString()) as Manifest;
+  }
+
+  it('should work for manifest v2', () => {
+    expect(
+      runWith({
+        'content_scripts/content-0': [
+          'content_scripts/content-0.css',
+          'content_scripts/content-0.js.map',
+        ],
+        'content_scripts/content-1': [
+          'content_scripts/content-1.css',
+          'content_scripts/content-1.js.map',
+        ],
+      }, {
+        manifest_version: 2,
+        content_scripts: [
+          {
+            matches: ['<all_urls>'],
+            run_at: 'document_start',
+            js: [
+              'content_scripts/content-0.js'
+            ],
+            css: []
+          },
+          {
+            matches: ['<all_urls>'],
+            run_at: 'document_start',
+            js: [
+              'content_scripts/content-1.js'
+            ],
+            css: []
+          }
+        ]
+      })
+    ).toMatchObject({
+      web_accessible_resources: [
+        'content_scripts/content-0.css',
+        'content_scripts/content-0.js.map',
+        'content_scripts/content-1.css',
+        'content_scripts/content-1.js.map',
+      ]
+    });
+  });
+
+  it('should work for manifest v3', () => {
+    expect(
+      runWith({
+        'content_scripts/content-0': [
+          'content_scripts/content-0.css',
+          'content_scripts/content-0.js.map',
+        ],
+        'content_scripts/content-1': [
+          'content_scripts/content-1.css',
+          'content_scripts/content-1.js.map',
+        ],
+      }, {
+        manifest_version: 3,
+        content_scripts: [
+          {
+            matches: ['<all_urls>'],
+            run_at: 'document_start',
+            js: [
+              'content_scripts/content-0.js'
+            ],
+            css: []
+          },
+          {
+            matches: ['<all_urls>'],
+            run_at: 'document_start',
+            js: [
+              'content_scripts/content-1.js'
+            ],
+            css: []
+          }
+        ]
+      })
+    ).toMatchObject({
+      web_accessible_resources: [
+        {
+          matches: ['<all_urls>'],
+          resources: [
+            'content_scripts/content-0.css',
+            'content_scripts/content-1.css',
+          ],
+        }
+      ]
+    });
+  });
+
+  it('should work if there is existing web_accessible_resources', () => {
+    expect(
+      runWith({
+        'content_scripts/content-0': [
+          'content_scripts/content-0.css',
+          'content_scripts/content-0.js.map',
+        ],
+        'content_scripts/content-1': [
+          'content_scripts/content-1.css',
+          'content_scripts/content-1.js.map',
+        ],
+      }, {
+        manifest_version: 3,
+        content_scripts: [
+          {
+            matches: ['<all_urls>'],
+            run_at: 'document_start',
+            js: [
+              'content_scripts/content-0.js'
+            ],
+            css: []
+          },
+          {
+            matches: ['https://example.com/some/path'],
+            run_at: 'document_start',
+            js: [
+              'content_scripts/content-1.js'
+            ],
+            css: []
+          }
+        ],
+        web_accessible_resources: [
+          {
+            matches: ['<all_urls>'],
+            resources: [
+              'my-file.css',
+            ],
+          }
+        ]
+      })
+    ).toMatchObject({
+      web_accessible_resources: [
+        {
+          matches: ['<all_urls>'],
+          resources: [
+            'my-file.css',
+            'content_scripts/content-0.css',
+          ],
+        },
+        {
+          matches: ['https://example.com/*'],
+          resources: [
+            'content_scripts/content-1.css',
+          ],
+        }
+      ]
+    });
+  });
+
+  it('should not add web_accessible_resources if there is no entries', () => {
+    expect(
+      runWith({}, {
+        manifest_version: 3,
+        background: {
+          service_worker: 'background.js',
+        }
+      }).web_accessible_resources
+    ).toBeUndefined();
+  });
+});
diff --git a/programs/develop/webpack/plugin-extension/feature-web-resources/index.ts b/programs/develop/webpack/plugin-extension/feature-web-resources/index.ts
index 2228bdb3..fbac7a6c 100644
--- a/programs/develop/webpack/plugin-extension/feature-web-resources/index.ts
+++ b/programs/develop/webpack/plugin-extension/feature-web-resources/index.ts
@@ -56,7 +56,7 @@ export class WebResourcesPlugin {
 
           if (existingResource) {
             resources.forEach((resource) => {
-              if (!existingResource.resources.includes(resource)) {
+              if (!existingResource.resources.includes(resource) && !resource.endsWith('.map')) {
                 existingResource.resources.push(resource)
               }
             })
@@ -81,13 +81,17 @@ export class WebResourcesPlugin {
     }
 
     if (manifest.manifest_version === 3) {
-      manifest.web_accessible_resources =
-        webAccessibleResourcesV3 as Manifest['web_accessible_resources']
+      if (webAccessibleResourcesV3.length > 0) {
+        manifest.web_accessible_resources =
+          webAccessibleResourcesV3 as Manifest['web_accessible_resources']
+      }
     } else {
-      // @ts-expect-error - web_accessible_resources is a string[] in V2
-      manifest.web_accessible_resources = Array.from(
-        new Set(webAccessibleResourcesV2)
-      )
+      if (webAccessibleResourcesV2.length > 0) {
+        // @ts-expect-error - web_accessible_resources is a string[] in V2
+        manifest.web_accessible_resources = Array.from(
+          new Set(webAccessibleResourcesV2)
+        )
+      }
     }
 
     const source = JSON.stringify(manifest, null, 2)