diff --git a/src/net/dnsconfig_unix.go b/src/net/dnsconfig_unix.go
index 94cd09ec710..3ba6d44fc3a 100644
--- a/src/net/dnsconfig_unix.go
+++ b/src/net/dnsconfig_unix.go
@@ -109,6 +109,9 @@ func dnsReadConfig(filename string) *dnsConfig {
 					// https://www.freebsd.org/cgi/man.cgi?query=resolv.conf&sektion=5&manpath=freebsd-release-ports
 					// https://man.openbsd.org/resolv.conf.5
 					conf.useTCP = true
+				case s == "edns0":
+					// We use EDNS by default.
+					// Ignore this option.
 				default:
 					conf.unknownOpt = true
 				}