diff --git a/src/aircraft_cmd.cpp b/src/aircraft_cmd.cpp
--- a/src/aircraft_cmd.cpp
+++ b/src/aircraft_cmd.cpp
@@ -530,7 +530,7 @@ CommandCost CmdStartStopAircraft(TileInd
 	/* Check if this aircraft can be started/stopped. The callback will fail or
 	 * return 0xFF if it can. */
 	uint16 callback = GetVehicleCallback(CBID_VEHICLE_START_STOP_CHECK, 0, 0, v->engine_type, v);
-	if (callback != CALLBACK_FAILED && callback != 0xFF) {
+	if (callback != CALLBACK_FAILED && GB(callback, 0, 8) != 0xFF) {
 		StringID error = GetGRFStringID(GetEngineGRFID(v->engine_type), 0xD000 + callback);
 		return_cmd_error(error);
 	}
diff --git a/src/industry_gui.cpp b/src/industry_gui.cpp
--- a/src/industry_gui.cpp
+++ b/src/industry_gui.cpp
@@ -78,8 +78,8 @@ static StringID GetCargoSuffix(uint carg
 {
 	if (HasBit(indspec->callback_flags, CBM_IND_CARGO_SUFFIX)) {
 		bool fund = ind == NULL;
-		uint8 callback = GetIndustryCallback(CBID_INDUSTRY_CARGO_SUFFIX, 0, ((!fund) ? 1 << 8 : 0) | cargo, ind, ind_type, (!fund) ? ind->xy : INVALID_TILE);
-		if (callback != 0xFF) return GetGRFStringID(indspec->grf_prop.grffile->grfid, 0xD000 + callback);
+		uint16 callback = GetIndustryCallback(CBID_INDUSTRY_CARGO_SUFFIX, 0, ((!fund) ? 1 << 8 : 0) | cargo, ind, ind_type, (!fund) ? ind->xy : INVALID_TILE);
+		if (GB(callback, 0, 8) != 0xFF) return GetGRFStringID(indspec->grf_prop.grffile->grfid, 0xD000 + callback);
 	}
 	return STR_EMPTY;
 }
diff --git a/src/roadveh_cmd.cpp b/src/roadveh_cmd.cpp
--- a/src/roadveh_cmd.cpp
+++ b/src/roadveh_cmd.cpp
@@ -293,19 +293,16 @@ CommandCost CmdBuildRoadVeh(TileIndex ti
  */
 CommandCost CmdStartStopRoadVeh(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	Vehicle *v;
-	uint16 callback;
-
 	if (!IsValidVehicleID(p1)) return CMD_ERROR;
 
-	v = GetVehicle(p1);
+	Vehicle *v = GetVehicle(p1);
 
 	if (v->type != VEH_ROAD || !CheckOwnership(v->owner)) return CMD_ERROR;
 
 	/* Check if this road veh can be started/stopped. The callback will fail or
 	 * return 0xFF if it can. */
-	callback = GetVehicleCallback(CBID_VEHICLE_START_STOP_CHECK, 0, 0, v->engine_type, v);
-	if (callback != CALLBACK_FAILED && callback != 0xFF) {
+	uint16 callback = GetVehicleCallback(CBID_VEHICLE_START_STOP_CHECK, 0, 0, v->engine_type, v);
+	if (callback != CALLBACK_FAILED && GB(callback, 0, 8) != 0xFF) {
 		StringID error = GetGRFStringID(GetEngineGRFID(v->engine_type), 0xD000 + callback);
 		return_cmd_error(error);
 	}
diff --git a/src/ship_cmd.cpp b/src/ship_cmd.cpp
--- a/src/ship_cmd.cpp
+++ b/src/ship_cmd.cpp
@@ -882,19 +882,16 @@ CommandCost CmdSellShip(TileIndex tile, 
  */
 CommandCost CmdStartStopShip(TileIndex tile, uint32 flags, uint32 p1, uint32 p2)
 {
-	Vehicle *v;
-	uint16 callback;
-
 	if (!IsValidVehicleID(p1)) return CMD_ERROR;
 
-	v = GetVehicle(p1);
+	Vehicle *v = GetVehicle(p1);
 
 	if (v->type != VEH_SHIP || !CheckOwnership(v->owner)) return CMD_ERROR;
 
 	/* Check if this ship can be started/stopped. The callback will fail or
 	 * return 0xFF if it can. */
-	callback = GetVehicleCallback(CBID_VEHICLE_START_STOP_CHECK, 0, 0, v->engine_type, v);
-	if (callback != CALLBACK_FAILED && callback != 0xFF) {
+	uint16 callback = GetVehicleCallback(CBID_VEHICLE_START_STOP_CHECK, 0, 0, v->engine_type, v);
+	if (callback != CALLBACK_FAILED && GB(callback, 0, 8) != 0xFF) {
 		StringID error = GetGRFStringID(GetEngineGRFID(v->engine_type), 0xD000 + callback);
 		return_cmd_error(error);
 	}
diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -1280,7 +1280,7 @@ CommandCost CmdStartStopTrain(TileIndex 
 	/* Check if this train can be started/stopped. The callback will fail or
 	 * return 0xFF if it can. */
 	uint16 callback = GetVehicleCallback(CBID_VEHICLE_START_STOP_CHECK, 0, 0, v->engine_type, v);
-	if (callback != CALLBACK_FAILED && callback != 0xFF) {
+	if (callback != CALLBACK_FAILED && GB(callback, 0, 8) != 0xFF) {
 		StringID error = GetGRFStringID(GetEngineGRFID(v->engine_type), 0xD000 + callback);
 		return_cmd_error(error);
 	}