diff --git a/firmware/slavechip/main.h b/firmware/slavechip/main.h
index 6dc28c2..4aa595d 100644
--- a/firmware/slavechip/main.h
+++ b/firmware/slavechip/main.h
@@ -15,6 +15,7 @@
 
 extern uint8_t foo;
 extern uint16_t bar;
+extern uint16_t timertmp;
 
 void baz();