diff --git a/src/tree_data_helpers.c b/src/tree_data_helpers.c
index 714b1fd..94b5fd1 100644
--- a/src/tree_data_helpers.c
+++ b/src/tree_data_helpers.c
@@ -934,6 +934,7 @@
         return LY_ESYS;
     }
 
+#ifdef HAVE_TM_GMTOFF
     /* get timezone offset */
     if (tm.tm_gmtoff == 0) {
         /* time is Zulu (UTC) */
@@ -945,6 +946,11 @@
         zonediff_m = tm.tm_gmtoff / 60 % 60;
     }
     sprintf(zoneshift, "%+03d:%02d", zonediff_h, zonediff_m);
+#else
+    (void)zonediff_h;
+    (void)zonediff_m;
+    sprintf(zoneshift, "-00:00");
+#endif
 
     /* print */
     if (asprintf(str, "%04d-%02d-%02dT%02d:%02d:%02d%s%s%s",