diff --git a/platforms/common/include/px4_platform_common/i2c.h b/platforms/common/include/px4_platform_common/i2c.h
index c7c02d1428..c40381fa67 100644
--- a/platforms/common/include/px4_platform_common/i2c.h
+++ b/platforms/common/include/px4_platform_common/i2c.h
@@ -84,7 +84,7 @@ public:
 
 	int externalBusIndex() const { return _external_bus_counter; }
 
-	bool external() const { return px4_i2c_bus_external(_bus); }
+	bool external() const { return px4_i2c_bus_external(bus().bus); }
 
 private:
 	const FilterType _filter;