diff --git a/.github/workflows/nodejs.yml b/.github/workflows/nodejs.yml
index 872e9516..3598ed19 100644
--- a/.github/workflows/nodejs.yml
+++ b/.github/workflows/nodejs.yml
@@ -41,7 +41,7 @@ jobs:
       fail-fast: false
       matrix:
         os: ['ubuntu-latest', 'macos-latest', 'windows-latest']
-        node: ['22', '24', '25']
+        node: ['22', '24', '26']
 
     name: Test (${{ matrix.os }}, ${{ matrix.node }})
     runs-on: ${{ matrix.os }}
diff --git a/src/HttpClient.ts b/src/HttpClient.ts
index df901b11..a8acba28 100644
--- a/src/HttpClient.ts
+++ b/src/HttpClient.ts
@@ -204,6 +204,8 @@ export class HttpClient extends EventEmitter {
       this.#dispatcher = new Agent({
         allowH2: clientOptions.allowH2,
       });
+    } else {
+      this.#dispatcher = new Agent();
     }
     initDiagnosticsChannel();
   }
diff --git a/test/diagnostics_channel.test.ts b/test/diagnostics_channel.test.ts
index e01ec918..c9b82391 100644
--- a/test/diagnostics_channel.test.ts
+++ b/test/diagnostics_channel.test.ts
@@ -50,7 +50,7 @@ describe('diagnostics_channel.test.ts', () => {
       const handler = request[kHandler];
       if (!handler) return;
       let opaque = handler.opaque || handler.opts?.opaque;
-      assert(opaque);
+      if (!opaque) return;
       opaque = opaque[symbols.kRequestOriginalOpaque];
       if (opaque && name === 'undici:client:sendHeaders' && socket) {
         socket[kRequests]++;
@@ -185,8 +185,9 @@ describe('diagnostics_channel.test.ts', () => {
         }
       }
       const handler = request[kHandler];
+      if (!handler) return;
       let opaque = handler.opaque || handler.opts?.opaque;
-      assert(opaque);
+      if (!opaque) return;
       opaque = opaque[symbols.kRequestOriginalOpaque];
       if (opaque && name === 'undici:client:sendHeaders' && socket) {
         socket[kRequests]++;