diff --git a/sys/dev/extres/phy/phy.c b/sys/dev/extres/phy/phy.c
index ab0929036c57..ac1feebf0425 100644
--- a/sys/dev/extres/phy/phy.c
+++ b/sys/dev/extres/phy/phy.c
@@ -68,7 +68,7 @@ static phynode_method_t phynode_methods[] = {
 DEFINE_CLASS_0(phynode, phynode_class, phynode_methods, 0);
 
 static phynode_list_t phynode_list = TAILQ_HEAD_INITIALIZER(phynode_list);
-
+struct sx phynode_topo_lock;
 SX_SYSINIT(phy_topology, &phynode_topo_lock, "Phy topology lock");
 
 /* ----------------------------------------------------------------------------
diff --git a/sys/dev/extres/phy/phy_internal.h b/sys/dev/extres/phy/phy_internal.h
index c2b985d68406..c4979a1dc739 100644
--- a/sys/dev/extres/phy/phy_internal.h
+++ b/sys/dev/extres/phy/phy_internal.h
@@ -78,6 +78,6 @@ struct phy {
 #define PHYNODE_XLOCK(_sc)	sx_xlock(&((_sc)->lock))
 #define PHYNODE_UNLOCK(_sc)	sx_unlock(&((_sc)->lock))
 
-struct sx		phynode_topo_lock;
+extern struct sx phynode_topo_lock;
 
 #endif /* DEV_EXTRES_PHY_INTERNAL_H */