diff --git a/include/openbsc/gsm_subscriber.h b/include/openbsc/gsm_subscriber.h
index 7da896e..46b674b 100644
--- a/include/openbsc/gsm_subscriber.h
+++ b/include/openbsc/gsm_subscriber.h
@@ -12,7 +12,7 @@
 #define GSM_EXTENSION_LENGTH 128
 
 struct gsm_subscriber {
-	u_int64_t id;
+	long unsigned int id;
 	char imsi[GSM_IMSI_LENGTH];
 	char tmsi[GSM_TMSI_LENGTH];
 	u_int16_t lac;