diff --git a/hook.js b/hook.js
index e446457..0ec34a4 100644
--- a/hook.js
+++ b/hook.js
@@ -115,7 +115,7 @@ function createHook (meta) {
     specifiers.set(url.url, specifier)
     
     return {
-      url: url.format !== 'module' ? addIitm(url.url) : url.url,
+      url: url.format !== 'module' || NODE_MAJOR < 16 ? addIitm(url.url) : url.url,
       shortCircuit: true,
       format: url.format
     }
@@ -143,7 +143,7 @@ register(${JSON.stringify(realUrl)}, namespace, set, ${JSON.stringify(specifiers
 `
       } 
     }
-    else if (context.format === 'module') {
+    else if (context.format === 'module' && NODE_MAJOR >= 16) {
       let fileContents
       try {
         fileContents = fs.readFileSync(fileURLToPath(url), 'utf8')
diff --git a/test/get-esm-exports/v20-get-esm-exports.js b/test/get-esm-exports/v16-get-esm-exports.js
similarity index 100%
rename from test/get-esm-exports/v20-get-esm-exports.js
rename to test/get-esm-exports/v16-get-esm-exports.js
diff --git a/test/hook/v20-declaration-exports.mjs b/test/hook/v16-declaration-exports.mjs
similarity index 100%
rename from test/hook/v20-declaration-exports.mjs
rename to test/hook/v16-declaration-exports.mjs
diff --git a/test/hook/v20-default-exports.mjs b/test/hook/v16-default-exports.mjs
similarity index 100%
rename from test/hook/v20-default-exports.mjs
rename to test/hook/v16-default-exports.mjs
diff --git a/test/hook/v20-list-exports.mjs b/test/hook/v16-list-exports.mjs
similarity index 100%
rename from test/hook/v20-list-exports.mjs
rename to test/hook/v16-list-exports.mjs
diff --git a/test/hook/v18-static-import-assert.mjs b/test/hook/v16-static-import-assert.mjs
similarity index 100%
rename from test/hook/v18-static-import-assert.mjs
rename to test/hook/v16-static-import-assert.mjs
diff --git a/test/other/cyclical-dependency.mjs b/test/other/v16-cyclical-dependency.mjs
similarity index 100%
rename from test/other/cyclical-dependency.mjs
rename to test/other/v16-cyclical-dependency.mjs