diff --git a/sys/rpc/clnt_vc.c b/sys/rpc/clnt_vc.c
--- a/sys/rpc/clnt_vc.c
+++ b/sys/rpc/clnt_vc.c
@@ -206,6 +206,13 @@
 		sopt.sopt_val = &one;
 		sopt.sopt_valsize = sizeof(one);
 		sosetopt(so, &sopt);
+
+		sopt.sopt_dir = SOPT_SET;
+		sopt.sopt_level = IPPROTO_TCP;
+		sopt.sopt_name = TCP_USE_DDP;
+		sopt.sopt_val = &one;
+		sopt.sopt_valsize = sizeof(one);
+		sosetopt(so, &sopt);
 	}
 
 	ct->ct_closeit = FALSE;
diff --git a/sys/rpc/svc_vc.c b/sys/rpc/svc_vc.c
--- a/sys/rpc/svc_vc.c
+++ b/sys/rpc/svc_vc.c
@@ -287,6 +287,13 @@
 		if (error) {
 			return (NULL);
 		}
+
+		opt.sopt_dir = SOPT_SET;
+		opt.sopt_level = IPPROTO_TCP;
+		opt.sopt_name = TCP_USE_DDP;
+		opt.sopt_val = &one;
+		opt.sopt_valsize = sizeof(one);
+		(void)sosetopt(so, &opt);
 	}
 
 	cd = mem_alloc(sizeof(*cd));