diff --git a/steps-guix/loopback-bind-127001/files/loopback-bind-127001.c b/steps-guix/loopback-bind-127001/files/loopback-bind-127001.c
index d1dcf7b2..b62862bc 100644
--- a/steps-guix/loopback-bind-127001/files/loopback-bind-127001.c
+++ b/steps-guix/loopback-bind-127001/files/loopback-bind-127001.c
@@ -1,3 +1,7 @@
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>