diff --git a/sys/dev/sfxge/common/efx_mcdi.h b/sys/dev/sfxge/common/efx_mcdi.h
index e77581a2fa42..f25fb4eb6227 100644
--- a/sys/dev/sfxge/common/efx_mcdi.h
+++ b/sys/dev/sfxge/common/efx_mcdi.h
@@ -101,7 +101,7 @@ efx_mcdi_ev_cpl(
 	__in		int errcode);
 
 #if EFSYS_OPT_MCDI_PROXY_AUTH
-	__checkReturn	efx_rc_t
+extern	__checkReturn	efx_rc_t
 efx_mcdi_get_proxy_handle(
 	__in		efx_nic_t *enp,
 	__in		efx_mcdi_req_t *emrp,