diff --git a/openbsc/src/libmsc/gsm_04_11.c b/openbsc/src/libmsc/gsm_04_11.c
index ee7f577..76c3720 100644
--- a/openbsc/src/libmsc/gsm_04_11.c
+++ b/openbsc/src/libmsc/gsm_04_11.c
@@ -32,6 +32,8 @@
 #include <time.h>
 #include <netinet/in.h>
 
+#include "bscconfig.h"
+
 #include <osmocom/core/msgb.h>
 #include <osmocom/gsm/tlv.h>
 #include <openbsc/debug.h>
@@ -279,7 +281,12 @@
 	*scts++ = bcdify(tm->tm_hour);
 	*scts++ = bcdify(tm->tm_min);
 	*scts++ = bcdify(tm->tm_sec);
+#ifdef HAVE_TM_GMTOFF_IN_TM
 	*scts++ = bcdify(tm->tm_gmtoff/(60*15));
+#else
+#warning find a portable way to obtain timezone offset
+	*scts++ = 0;
+#endif
 }
 
 /* Decode 03.40 TP-SCTS (into utc/gmt timestamp) */
@@ -300,7 +307,9 @@
 	tm.tm_sec  = unbcdify(*scts++);
 	/* according to gsm 03.40 time zone is
 	   "expressed in quarters of an hour" */
+#ifdef HAVE_TM_GMTOFF_IN_TM
 	tm.tm_gmtoff = unbcdify(*scts++) * 15*60;
+#endif
 
 	return mktime(&tm);
 }