diff --git a/src/openvpn/route.c b/src/openvpn/route.c
index 5f63fd34..a302746e 100644
--- a/src/openvpn/route.c
+++ b/src/openvpn/route.c
@@ -3349,7 +3349,7 @@ get_default_gateway_ipv6(struct route_ipv6_gateway_info *rgi6,
             rgi6->flags |= RGI_ADDR_DEFINED;
         }
 
-        if (rgi6->iface)
+        if (strlen(rgi6->iface))
         {
             rgi6->flags |= RGI_IFACE_DEFINED;
         }