diff --git a/src/options.ts b/src/options.ts
index d05a1bc7..8026172c 100644
--- a/src/options.ts
+++ b/src/options.ts
@@ -16,6 +16,8 @@ export function resolveJitiOptions(userOptions: JitiOptions): JitiOptions {
       ".cjs",
       ".ts",
       ".tsx",
+      ".mts",
+      ".cts",
     ]),
     alias: _jsonEnv<Record<string, string>>("JITI_ALIAS", {}),
     nativeModules: _jsonEnv<string[]>("JITI_NATIVE_MODULES", []),
diff --git a/src/require.ts b/src/require.ts
index df3ec3fd..c8836fea 100644
--- a/src/require.ts
+++ b/src/require.ts
@@ -82,7 +82,13 @@ export function jitiRequire(
 
   // Unknown format
   if (ext && !ctx.opts.extensions!.includes(ext)) {
-    debug(ctx, "[unknown]", filename);
+    debug(
+      ctx,
+      "[native]",
+      "[unknown]",
+      opts.async ? "[import]" : "[require]",
+      filename,
+    );
     return nativeImportOrRequire(ctx, id, opts.async);
   }
 
diff --git a/src/resolve.ts b/src/resolve.ts
index 9cbbe03e..3c640140 100644
--- a/src/resolve.ts
+++ b/src/resolve.ts
@@ -56,7 +56,10 @@ export function jitiResolve(
       return resolved;
     }
     // Try resolving .ts files with .js extension
-    if (TS_EXT_RE.test(ctx.parentModule?.filename || "")) {
+    if (
+      TS_EXT_RE.test(ctx.filename) ||
+      TS_EXT_RE.test(ctx.parentModule?.filename || "")
+    ) {
       resolved = tryNativeRequireResolve(
         ctx,
         id.replace(JS_EXT_RE, ".$1t$2"),
diff --git a/src/utils.ts b/src/utils.ts
index 9bb3d0c1..d35ec01a 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -65,6 +65,7 @@ const debugMap = {
   "[native]": cyan("[native]"),
   "[transpile]": yellow("[transpile]"),
   "[fallback]": red("[fallback]"),
+  "[unknown]": red("[unknown]"),
   "[hit]": green("[hit]"),
   "[miss]": yellow("[miss]"),
 };
diff --git a/test/register-test.mjs b/test/register-test.mjs
index 876764be..87844ae2 100644
--- a/test/register-test.mjs
+++ b/test/register-test.mjs
@@ -9,9 +9,6 @@ const fixturesDir = fileURLToPath(new URL("fixtures", import.meta.url));
 const fixtures = await readdir(fixturesDir);
 
 for (const fixture of fixtures) {
-  if (fixture === "typescript") {
-    continue; // .mts support
-  }
   test("fixtures/" + fixture + " (ESM)", async () => {
     const promise = import(`./fixtures/${fixture}`);
     const shouldReject =