diff --git a/CHANGES b/CHANGES
index 9496d97a1..ca460464c 100644
--- a/CHANGES
+++ b/CHANGES
@@ -7,6 +7,7 @@ Features:
 Emulation fixes:
  - GB Audio: Fix channels 1/2 staying muted if restarted after long silence
  - GB Serialize: Add missing Pocket Cam state to savestates
+ - GB SIO: Disabling SIO should cancel pending transfers (fixes mgba.io/i/2537)
  - GB Video: Implement DMG-style sprite ordering
  - GBA BIOS: Fix clobbering registers with word-sized CpuSet
  - GBA Video: Disable BG target 1 blending when OBJ blending (fixes mgba.io/i/2722)
diff --git a/src/gb/sio.c b/src/gb/sio.c
index d327b606d..649213168 100644
--- a/src/gb/sio.c
+++ b/src/gb/sio.c
@@ -91,11 +91,13 @@ void GBSIOWriteSB(struct GBSIO* sio, uint8_t sb) {
 void GBSIOWriteSC(struct GBSIO* sio, uint8_t sc) {
 	sio->period = GBSIOCyclesPerTransfer[GBRegisterSCGetClockSpeed(sc)]; // TODO Shift Clock
 	if (GBRegisterSCIsEnable(sc)) {
-		mTimingDeschedule(&sio->p->timing, &sio->event);
 		if (GBRegisterSCIsShiftClock(sc)) {
+			mTimingDeschedule(&sio->p->timing, &sio->event);
 			mTimingSchedule(&sio->p->timing, &sio->event, sio->period * (2 - sio->p->doubleSpeed));
 			sio->remainingBits = 8;
 		}
+	} else {
+		mTimingDeschedule(&sio->p->timing, &sio->event);
 	}
 	if (sio->driver) {
 		sio->driver->writeSC(sio->driver, sc);