diff --git a/firmware/src_simtrace/card_emu.c b/firmware/src_simtrace/card_emu.c
index 1da453af..5eef7164 100644
--- a/firmware/src_simtrace/card_emu.c
+++ b/firmware/src_simtrace/card_emu.c
@@ -141,7 +141,7 @@ struct card_handle {
 	} stats;
 };
 
-static int update_fidi(struct card_handle *ch)
+static void update_fidi(struct card_handle *ch)
 {
 	int rc;