diff --git a/src/openvpn/route.c b/src/openvpn/route.c
index d18acd016..0d04a5a33 100644
--- a/src/openvpn/route.c
+++ b/src/openvpn/route.c
@@ -1541,13 +1541,15 @@ local_route(in_addr_t network,
     return LR_NOMATCH;
 }
 
-/* Return true if the "on-link" form of the route should be used.  This is when the gateway for a
+/* Return true if the "on-link" form of the route should be used.  This is when the gateway for
  * a route is specified as an interface rather than an address. */
+#if defined(TARGET_LINUX) || defined(_WIN32) || defined(TARGET_DARWIN)
 static inline bool
 is_on_link(const int is_local_route, const unsigned int flags, const struct route_gateway_info *rgi)
 {
     return rgi && (is_local_route == LR_MATCH || ((flags & ROUTE_REF_GW) && (rgi->flags & RGI_ON_LINK)));
 }
+#endif
 
 bool
 add_route(struct route_ipv4 *r,