diff --git a/sysdeps/mach/hurd/errnos.h b/sysdeps/mach/hurd/errnos.h
index acc9951706..ad73f1b9ac 100644
--- a/sysdeps/mach/hurd/errnos.h
+++ b/sysdeps/mach/hurd/errnos.h
@@ -274,6 +274,7 @@ enum __error_t_codes
    symbolic values.  */
 #ifdef __USE_GNU
 typedef enum __error_t_codes error_t;
+#define __error_t_defined	1
 #endif
 
 /* errno is a per-thread variable.  */