diff --git a/devices/geiger/gqgmc.go b/devices/geiger/gqgmc.go
index 257184ac8db9f810a811f1ebe076be88de52eaa4..de93e88bc6d261286beb76dd4fbe89eb7f59bff9 100644
--- a/devices/geiger/gqgmc.go
+++ b/devices/geiger/gqgmc.go
@@ -110,7 +110,7 @@ type DevConfig struct {
 	SensitivityMode              int8  `struct:"int8"`
 	CounterDelay                 int16 `struct:"int16,big"`
 	VoltageOffset                int8  `struct:"int8"`
-	MaxCPM                       int16 `struct:"int16,big"`
+	MaxCPM                       int16 `struct:"uint16,big"`
 	SensitivityAutoModeThreshold int8  `struct:"int8"`
 	SaveDateTimeStamp6           byte  `struct:"byte"`
 	SaveDateTimeStamp5           byte  `struct:"byte"`