diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index 2e83b77bd..efd2eee5d 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -15,8 +15,9 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
+        node: [18, 20, 22]
 
-    name: stable - ${{ matrix.os }} - node@20
+    name: stable - ${{ matrix.os }} - node@${{ matrix.node }}
     runs-on: ${{ matrix.os }}
 
     steps:
@@ -27,7 +28,7 @@ jobs:
       - name: Setup node
         uses: actions/setup-node@v4
         with:
-          node-version: 20
+          node-version: ${{ matrix.node }}
           cache: 'pnpm'
 
       - name: 'Install dependencies'
@@ -55,18 +56,13 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
+      - uses: pnpm/action-setup@v4
+
       - name: Setup node
         uses: actions/setup-node@v4
         with:
           node-version: 20
-
-      - name: Cache NPM dependencies
-        uses: actions/cache@v4
-        with:
-          path: ~/.pnpm-store
-          key: npm-cache-ubuntu-latest-node@20
-
-      - uses: pnpm/action-setup@v4
+          cache: 'pnpm'
 
       - name: 'Install dependencies'
         run: pnpm install
diff --git a/packages/register/esm.mts b/packages/register/esm.mts
index c913ac288..6f62babc0 100644
--- a/packages/register/esm.mts
+++ b/packages/register/esm.mts
@@ -279,6 +279,14 @@ export const load: LoadHook = async (url, context, nextLoad) => {
 
   const { source, format: resolvedFormat } = await nextLoad(url, context)
 
+  if (!source) {
+    debug('No source', url, resolvedFormat)
+    return {
+      source,
+      format: resolvedFormat,
+    }
+  }
+
   debug('loaded', url, resolvedFormat)
 
   const code = !source || typeof source === 'string' ? source : Buffer.from(source).toString()