diff --git a/firmware/ice40-riscv/icE1usb/misc.c b/firmware/ice40-riscv/icE1usb/misc.c
index a25bcc5..4b32fcd 100644
--- a/firmware/ice40-riscv/icE1usb/misc.c
+++ b/firmware/ice40-riscv/icE1usb/misc.c
@@ -71,9 +71,9 @@
 }
 
 uint16_t
-e1_tick_read(void)
+e1_tick_read(int port)
 {
-	return misc_regs->e1_tick[0].tx;
+	return misc_regs->e1_tick[port].tx;
 }
 
 void