diff --git a/.gitmodules b/.gitmodules
index 730f222..f1c7686 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,3 @@
 [submodule "test/usart"]
 	path = test/usart
-	url = https://git.chch.tech/avr/usart.git
+	url = git@git.chch.tech:avr/usart.git