diff --git a/src/drivers/px4flow/px4flow.cpp b/src/drivers/px4flow/px4flow.cpp
index 0fecb67b77..1cb7fa94a0 100644
--- a/src/drivers/px4flow/px4flow.cpp
+++ b/src/drivers/px4flow/px4flow.cpp
@@ -754,6 +754,10 @@ start(int argc, char *argv[])
 #ifdef PX4_I2C_BUS_ONBOARD
 			PX4_I2C_BUS_ONBOARD,
 #endif
+#ifdef PX4_I2C_BUS_EXPANSION1
+			PX4_I2C_BUS_EXPANSION1,
+#endif
+
 			-1
 		};