diff --git a/.gitmodules b/.gitmodules
index 7f4c674e..0933aaa3 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,3 +4,6 @@
 [submodule "app/ucglib/ucg"]
         path = app/ucglib/ucg
         url = https://github.com/olikraus/Ucglib_Arduino.git
+[submodule "app/libc/c99-snprintf"]
+	path = app/libc/c99-snprintf
+	url = https://github.com/weiss/c99-snprintf.git