diff --git a/wgengine/magicsock/peermtu_linux.go b/wgengine/magicsock/peermtu_linux.go
index b803f1a26..2f971e9c9 100644
--- a/wgengine/magicsock/peermtu_linux.go
+++ b/wgengine/magicsock/peermtu_linux.go
@@ -21,7 +21,7 @@ func setDontFragment(pconn nettype.PacketConn, network string) (err error) {
 					err = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IP, syscall.IP_MTU_DISCOVER, syscall.IP_PMTUDISC_DO)
 				}
 				if network == "udp6" {
-					err = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IPV6, syscall.IP_MTU_DISCOVER, syscall.IP_PMTUDISC_DO)
+					err = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_IPV6, syscall.IPV6_MTU_DISCOVER, syscall.IP_PMTUDISC_DO)
 				}
 			})
 		}