diff --git a/src/hlua.c b/src/hlua.c
index cb5feb5..5f5b2c3 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -3957,7 +3957,7 @@
 		int32_t pos;
 
 		blk = htx_get_first_blk(htx);
-		BUG_ON(htx_get_blk_type(blk) != HTX_BLK_REQ_SL);
+		BUG_ON(!blk || htx_get_blk_type(blk) != HTX_BLK_REQ_SL);
 		sl = htx_get_blk_ptr(htx, blk);
 
 		/* Stores the request method. */
diff --git a/src/mux_h2.c b/src/mux_h2.c
index a0fb93d..fd039d1 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -4586,7 +4586,7 @@
 
 	/* get the start line, we do have one */
 	blk = htx_get_head_blk(htx);
-	BUG_ON(htx_get_blk_type(blk) != HTX_BLK_RES_SL);
+	BUG_ON(!blk || htx_get_blk_type(blk) != HTX_BLK_RES_SL);
 	ALREADY_CHECKED(blk);
 	sl = htx_get_blk_ptr(htx, blk);
 	h2s->status = sl->info.res.status;
@@ -4795,7 +4795,7 @@
 
 	/* get the start line, we do have one */
 	blk = htx_get_head_blk(htx);
-	BUG_ON(htx_get_blk_type(blk) != HTX_BLK_REQ_SL);
+	BUG_ON(!blk || htx_get_blk_type(blk) != HTX_BLK_REQ_SL);
 	ALREADY_CHECKED(blk);
 	sl = htx_get_blk_ptr(htx, blk);
 	meth = htx_sl_req_meth(sl);
diff --git a/src/stats.c b/src/stats.c
index 0a0ed1d..e04ae92 100644
--- a/src/stats.c
+++ b/src/stats.c
@@ -283,7 +283,7 @@
 		struct ist uri;
 
 		blk = htx_get_head_blk(htx);
-		BUG_ON(htx_get_blk_type(blk) != HTX_BLK_REQ_SL);
+		BUG_ON(!blk || htx_get_blk_type(blk) != HTX_BLK_REQ_SL);
 		ALREADY_CHECKED(blk);
 		uri = htx_sl_req_uri(htx_get_blk_ptr(htx, blk));
 		p = uri.ptr;