diff --git a/cubesatsim/cubesatsim.h b/cubesatsim/cubesatsim.h
index ab169769..d48239fd 100644
--- a/cubesatsim/cubesatsim.h
+++ b/cubesatsim/cubesatsim.h
@@ -103,7 +103,7 @@ void send_packet();
 void read_ina219();
 void read_sensors();
 void get_tlm_ao7();
-void print_string();
+void print_string(*string);
 
 extern int Encode_8b10b[][256];