diff --git a/src/index.js b/src/index.js
index a6fb623e..0071a15f 100644
--- a/src/index.js
+++ b/src/index.js
@@ -531,7 +531,7 @@ function ncc (
       const baseDir = dirname(filename);
       const pjsonPath = (baseDir === '.' ? '' : baseDir) + 'package.json';
       if (assets[pjsonPath])
-        assets[pjsonPath].source = JSON.stringify(Object.assign(JSON.parse(pjsonPath.source.toString()), { type: 'module' }));
+        assets[pjsonPath].source = JSON.stringify(Object.assign(JSON.parse(assets[pjsonPath].source.toString()), { type: 'module' }));
       else
         assets[pjsonPath] = { source: JSON.stringify({ type: 'module' }, null, 2) + '\n', permissions: defaultPermissions };
     }
diff --git a/test/cli.js b/test/cli.js
index 514c01d1..84858c8a 100644
--- a/test/cli.js
+++ b/test/cli.js
@@ -11,6 +11,10 @@
     args: ["run", "test/integration/test.ts"],
     expect: { code: 0 }
   },
+  {
+    args: ["build", "test/fixtures/type-module/main.js", "-o", "tmp"],
+    expect: { code: 0 }
+  },
   {
     args: ["build", "test/integration/test.ts", "-o", "tmp"],
     expect (code, stdout, stderr) {
diff --git a/test/fixtures/type-module/main.js b/test/fixtures/type-module/main.js
new file mode 100644
index 00000000..20973d83
--- /dev/null
+++ b/test/fixtures/type-module/main.js
@@ -0,0 +1,6 @@
+import { readFileSync } from 'fs';
+
+readFileSync(new URL('./package.json', import.meta.url));
+
+export var p = 5;
+
diff --git a/test/fixtures/type-module/package.json b/test/fixtures/type-module/package.json
new file mode 100644
index 00000000..3dbc1ca5
--- /dev/null
+++ b/test/fixtures/type-module/package.json
@@ -0,0 +1,3 @@
+{
+  "type": "module"
+}