diff --git a/libs/libc/pthread/pthread_mutexattr_setprotocol.c b/libs/libc/pthread/pthread_mutexattr_setprotocol.c
index 47116b94de..ecf7e40626 100644
--- a/libs/libc/pthread/pthread_mutexattr_setprotocol.c
+++ b/libs/libc/pthread/pthread_mutexattr_setprotocol.c
@@ -69,6 +69,6 @@ int pthread_mutexattr_setprotocol(FAR pthread_mutexattr_t *attr,
       return OK;
     }
 
-  return ENOSYS;
+  return EINVAL;
 #endif
 }