diff --git a/impl/src/layer2/layer2_tx.c b/impl/src/layer2/layer2_tx.c
index 3f9815a..8277ca1 100644
--- a/impl/src/layer2/layer2_tx.c
+++ b/impl/src/layer2/layer2_tx.c
@@ -62,13 +62,14 @@ result_t layer2_tx_fill_packet_queue(layer2_tx_t *ctx)
 			// a packet is available -> move it to the queue
 			header.tx_seq_nr = ctx->next_seq_nr;
 
-			uint8_t *packetbuf = malloc(2048);
+			static const size_t packetbuf_size = 2048;
+			uint8_t *packetbuf = malloc(packetbuf_size);
 			if(!packetbuf) {
 				LOG(LVL_ERR, "malloc failed.");
 				return ERR_NO_MEM;
 			}
 
-			ret = read(ctx->tun_fd, packetbuf, sizeof(packetbuf));
+			ret = read(ctx->tun_fd, packetbuf, packetbuf_size);
 			if(ret < 0) {
 				LOG(LVL_ERR, "read: %s", strerror(errno));
 				free(packetbuf);