diff --git a/drivers/char/diag/diagchar_core.c b/drivers/char/diag/diagchar_core.c
index 4885412dd014..ed982f426923 100644
--- a/drivers/char/diag/diagchar_core.c
+++ b/drivers/char/diag/diagchar_core.c
@@ -389,8 +389,8 @@ static int diagchar_open(struct inode *inode, struct file *file)
 	return -ENOMEM;
 
 fail:
-	mutex_unlock(&driver->diagchar_mutex);
 	driver->num_clients--;
+	mutex_unlock(&driver->diagchar_mutex);
 	pr_err_ratelimited("diag: Insufficient memory for new client");
 	return -ENOMEM;
 }