diff --git a/firmware/libcommon/source/card_emu.c b/firmware/libcommon/source/card_emu.c
index ed3aa99..98b08d7 100644
--- a/firmware/libcommon/source/card_emu.c
+++ b/firmware/libcommon/source/card_emu.c
@@ -165,7 +165,7 @@
 /* update simtrace header msg_len and submit USB buffer */
 void usb_buf_upd_len_and_submit(struct msgb *msg)
 {
-	struct simtrace_msg_hdr *sh = msg->l1h;
+	struct simtrace_msg_hdr *sh = (struct simtrace_msg_hdr *) msg->l1h;
 
 	sh->msg_len = msgb_length(msg);