diff --git a/auto/unix b/auto/unix
index 6e54531c9..b90ba3c46 100755
--- a/auto/unix
+++ b/auto/unix
@@ -304,7 +304,7 @@ ngx_feature_run=no
 ngx_feature_incs="#include <sys/socket.h>"
 ngx_feature_path=
 ngx_feature_libs=
-ngx_feature_test="setsockopt(0, SOL_SOCKET, SO_SETFIB, NULL, 4)"
+ngx_feature_test="setsockopt(0, SOL_SOCKET, SO_SETFIB, NULL, 0)"
 . auto/feature