diff --git a/src/gps/GPS.h b/src/gps/GPS.h
index b4716af76..836114d2e 100644
--- a/src/gps/GPS.h
+++ b/src/gps/GPS.h
@@ -137,7 +137,7 @@ class GPS : private concurrency::OSThread
 
     GpsOperation getGpsOp() const;
 
-    bool getACK(uint8_t cl, uint8_t id);
+    bool getACK(uint8_t c, uint8_t i);
 
     /**
      * Tell users we have new GPS readings