make GNU expose tm_gmtoff and tm_zone

1 files changed, 6 insertions, 0 deletions

diff --git a/src/date.h b/src/date.h
index 6a3f73c..d4b0680 100644
--- a/src/date.h
+++ b/src/date.h
@@ -1,4 +1,10 @@
 #pragma once
+// compatibility flags
+
+// GNU-ish systems require this to expose tm_gmtoff and tm_zone
+// this is important because of how we detect their existence
+#define _GNU_SOURCE 1
+
 #include <janet.h>
 #include <time.h>
 #include "polyfill.h"