diff --git a/libs/freetdm/src/ftmod/ftmod_sangoma_isdn/ftmod_sangoma_isdn.c b/libs/freetdm/src/ftmod/ftmod_sangoma_isdn/ftmod_sangoma_isdn.c
index 8fea822101..654db0ff10 100644
--- a/libs/freetdm/src/ftmod/ftmod_sangoma_isdn/ftmod_sangoma_isdn.c
+++ b/libs/freetdm/src/ftmod/ftmod_sangoma_isdn/ftmod_sangoma_isdn.c
@@ -342,7 +342,7 @@ static void ftdm_sangoma_isdn_wakeup_phy(ftdm_channel_t *dchan)
 static void *ftdm_sangoma_isdn_io_run(ftdm_thread_t *me, void *obj)
 {
 	uint8_t data[1000];
-	unsigned i;
+	unsigned i = 0;
 	ftdm_status_t status = FTDM_SUCCESS;
 	ftdm_wait_flag_t wflags = FTDM_READ;
 	ftdm_span_t *span = (ftdm_span_t*) obj;