diff --git a/src/add-ons/kernel/generic/mpu401/mpu401.c b/src/add-ons/kernel/generic/mpu401/mpu401.c
index e68c99e2ec..cb61dc3f28 100644
--- a/src/add-ons/kernel/generic/mpu401/mpu401.c
+++ b/src/add-ons/kernel/generic/mpu401/mpu401.c
@@ -237,7 +237,7 @@ midi_close(void * cookie)
 	delete_sem(mpu_device->writesemaphore);
 
 	atomic_add(&mpu_device->count, -1);
-  	PRINT(("midi_close() done (count = %lu)\n", mpu_device->count));
+  	PRINT(("midi_close() done (count = %" B_PRId32 ")\n", mpu_device->count));
 
 	return B_OK;
 }