diff --git a/cubesatsim/cubesatsim.h b/cubesatsim/cubesatsim.h
index c5cb556c..110098c8 100644
--- a/cubesatsim/cubesatsim.h
+++ b/cubesatsim/cubesatsim.h
@@ -164,7 +164,7 @@ int uart_fd;
 
 int reset_count = 0;
 float uptime_sec = 0;
-long int uptime;
+long int uptime = 0;
 char call[5];
 char sim_yes[10];