diff --git a/src/gsm/lapd_core.c b/src/gsm/lapd_core.c
index f351308..9dbdfcf 100644
--- a/src/gsm/lapd_core.c
+++ b/src/gsm/lapd_core.c
@@ -327,6 +327,7 @@
 	lapd_dl_reset(dl);
 	/* free history buffer list */
 	talloc_free(dl->tx_hist);
+	dl->tx_hist = NULL;
 }
 
 /*! \brief Set the \ref lapdm_mode of a LAPDm entity */