diff --git a/sys/netinet/ip_gre.c b/sys/netinet/ip_gre.c
index ac28b6e4c18f..71068375cdb1 100644
--- a/sys/netinet/ip_gre.c
+++ b/sys/netinet/ip_gre.c
@@ -96,9 +96,9 @@
 void gre_inet_ntoa(struct in_addr in); 	/* XXX */
 #endif
 
-static struct gre_softc *gre_lookup __P((struct mbuf *, u_int8_t));
+static struct gre_softc *gre_lookup(struct mbuf *, u_int8_t);
 
-static int	gre_input2 __P((struct mbuf *, int, u_char));
+static int	gre_input2(struct mbuf *, int, u_char);
 
 /*
  * De-encapsulate a packet and feed it back through ip input (this
diff --git a/sys/netinet/ip_gre.h b/sys/netinet/ip_gre.h
index c3562bef14cc..b34baf6cdb1f 100644
--- a/sys/netinet/ip_gre.h
+++ b/sys/netinet/ip_gre.h
@@ -38,6 +38,6 @@
  */
 
 #ifdef _KERNEL
-void gre_input __P((struct mbuf *, ...));
-void gre_mobile_input __P((struct mbuf *, ...));
+void gre_input(struct mbuf *, ...);
+void gre_mobile_input(struct mbuf *, ...);
 #endif /* _KERNEL */