diff --git a/src/esmockIsESMRe.js b/src/esmockIsESMRe.js
new file mode 100644
index 00000000..bc02dbd6
--- /dev/null
+++ b/src/esmockIsESMRe.js
@@ -0,0 +1,2 @@
+// eslint-disable-next-line max-len
+export default /(^\s*|[});\n]\s*)(import\s+(['"]|(\*\s+as\s+)?[^"'()\n;]+\s+from\s+['"]|\{)|export\s+\*\s+from\s+["']|export\s+(\{|default|function|class|var|const|let|async\s+function))/
diff --git a/src/esmockLoader.js b/src/esmockLoader.js
index d4d097b5..3eac82a7 100644
--- a/src/esmockLoader.js
+++ b/src/esmockLoader.js
@@ -141,13 +141,15 @@ const load = async (url, context, nextLoad) => {
       const source = String((await nextLoad(url, context)).source)
       const hbang = (source.match(hashbangRe) || [])[0] || ''
       const sourcesafe = hbang ? source.replace(hashbangRe, '') : source
+      const importexpr = context.format === 'module'
+        ? `import {${importedNames}} from '${specifier}';`
+        : `const {${importedNames}} = require('${specifier}');`
 
       return {
-        format: 'module',
+        format: context.format,
         shortCircuit: true,
         responseURL: encodeURI(url),
-        source: hbang + `import {${importedNames}} from '${specifier}';`
-          + sourcesafe
+        source: hbang + importexpr + sourcesafe
       }
     }
   }
diff --git a/src/esmockModule.js b/src/esmockModule.js
index 0e8b7372..53e87e9a 100644
--- a/src/esmockModule.js
+++ b/src/esmockModule.js
@@ -2,6 +2,7 @@ import fs from 'fs'
 import url from 'node:url'
 import resolvewith from 'resolvewithplus'
 import esmockErr from './esmockErr.js'
+import esmockIsESMRe from './esmockIsESMRe.js'
 
 import {
   esmockTreeIdSet,
@@ -65,9 +66,6 @@ const esmockModuleApply = (defLive, def, fileURL) => {
   return def
 }
 
-// eslint-disable-next-line max-len
-const esmockModuleESMRe = /(^\s*|[});\n]\s*)(import\s+(['"]|(\*\s+as\s+)?[^"'()\n;]+\s+from\s+['"]|\{)|export\s+\*\s+from\s+["']|export\s+(\{|default|function|class|var|const|let|async\s+function))/
-
 // returns cached results when available
 const esmockModuleIsESM = (fileURL, isesm) => {
   isesm = esmockCacheResolvedPathIsESMGet(fileURL)
@@ -77,7 +75,7 @@ const esmockModuleIsESM = (fileURL, isesm) => {
 
   isesm = !resolvewith.iscoremodule(fileURL)
     && isDirPathRe.test(fileURL)
-    && esmockModuleESMRe.test(fs.readFileSync(fileURL, 'utf-8'))
+    && esmockIsESMRe.test(fs.readFileSync(fileURL, 'utf-8'))
 
   esmockCacheResolvedPathIsESMSet(fileURL, isesm)