diff --git a/stm-firmware/shell.c b/stm-firmware/shell.c
index 4da429d..a34f0b7 100644
--- a/stm-firmware/shell.c
+++ b/stm-firmware/shell.c
@@ -93,7 +93,8 @@ static shellmatta_retCode_t shell_cmd_digio_set(const shellmatta_handle_t   hand
 	char buff[64];
 	char *curr_token;
 
-	strncpy(buff, arguments, sizeof(buff));
+	strncpy(buff, arguments, sizeof(buff)-1);
+	buff[63] = '\0';
 
 	curr_token = strtok(buff, " ");
 	curr_token = strtok(NULL, " ");