diff --git a/libusb/os/windows_common.c b/libusb/os/windows_common.c
index efb746b..a5e2a7c 100644
--- a/libusb/os/windows_common.c
+++ b/libusb/os/windows_common.c
@@ -415,8 +415,11 @@
 	DWORD num_bytes;
 	ULONG_PTR completion_key;
 	OVERLAPPED *overlapped;
+	struct libusb_device_handle *dev_handle;
+	struct windows_device_handle_priv *handle_priv;
 	struct windows_transfer_priv *transfer_priv;
 	struct usbi_transfer *itransfer;
+	bool found;
 
 	usbi_dbg("I/O completion thread started");
 
@@ -434,7 +437,29 @@
 			break;
 		}
 
-		transfer_priv = container_of(overlapped, struct windows_transfer_priv, overlapped);
+		// Find the transfer associated with the OVERLAPPED that just completed.
+		// If we cannot find a match, the I/O operation originated from outside of libusb
+		// (e.g. within libusbK) and we need to ignore it.
+		dev_handle = (struct libusb_device_handle *)completion_key;
+		handle_priv = usbi_get_device_handle_priv(dev_handle);
+		found = false;
+		usbi_mutex_lock(&dev_handle->lock);
+		list_for_each_entry(transfer_priv, &handle_priv->active_transfers, list, struct windows_transfer_priv) {
+			if (overlapped == &transfer_priv->overlapped) {
+				// This OVERLAPPED belongs to us, remove the transfer from the device handle's list
+				list_del(&transfer_priv->list);
+				found = true;
+				break;
+			}
+		}
+		usbi_mutex_unlock(&dev_handle->lock);
+
+		if (!found) {
+			usbi_dbg("ignoring overlapped %p for handle %p (device %u.%u)",
+				overlapped, dev_handle, dev_handle->dev->bus_number, dev_handle->dev->device_address);
+			continue;
+		}
+
 		itransfer = (struct usbi_transfer *)((unsigned char *)transfer_priv + PTR_ALIGN(sizeof(*transfer_priv)));
 		usbi_dbg("transfer %p completed, length %lu",
 			 USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer), ULONG_CAST(num_bytes));
@@ -613,6 +638,9 @@
 static int windows_open(struct libusb_device_handle *dev_handle)
 {
 	struct windows_context_priv *priv = usbi_get_context_priv(HANDLE_CTX(dev_handle));
+	struct windows_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+
+	list_init(&handle_priv->active_transfers);
 	return priv->backend->open(dev_handle);
 }
 
@@ -697,8 +725,10 @@
 static int windows_submit_transfer(struct usbi_transfer *itransfer)
 {
 	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-	struct libusb_context *ctx = TRANSFER_CTX(transfer);
+	struct libusb_device_handle *dev_handle = transfer->dev_handle;
+	struct libusb_context *ctx = HANDLE_CTX(dev_handle);
 	struct windows_context_priv *priv = usbi_get_context_priv(ctx);
+	struct windows_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
 	struct windows_transfer_priv *transfer_priv = usbi_get_transfer_priv(itransfer);
 	int r;
 
@@ -721,8 +751,18 @@
 		transfer_priv->handle = NULL;
 	}
 
+	// Add transfer to the device handle's list
+	usbi_mutex_lock(&dev_handle->lock);
+	list_add_tail(&transfer_priv->list, &handle_priv->active_transfers);
+	usbi_mutex_unlock(&dev_handle->lock);
+
 	r = priv->backend->submit_transfer(itransfer);
 	if (r != LIBUSB_SUCCESS) {
+		// Remove the unsuccessful transfer from the device handle's list
+		usbi_mutex_lock(&dev_handle->lock);
+		list_del(&transfer_priv->list);
+		usbi_mutex_unlock(&dev_handle->lock);
+
 		// Always call the backend's clear_transfer_priv() function on failure
 		priv->backend->clear_transfer_priv(itransfer);
 		transfer_priv->handle = NULL;
@@ -880,6 +920,6 @@
 	windows_handle_transfer_completion,
 	sizeof(struct windows_context_priv),
 	sizeof(union windows_device_priv),
-	sizeof(union windows_device_handle_priv),
+	sizeof(struct windows_device_handle_priv),
 	sizeof(struct windows_transfer_priv),
 };
diff --git a/libusb/os/windows_common.h b/libusb/os/windows_common.h
index d9958c6..c84f1f9 100644
--- a/libusb/os/windows_common.h
+++ b/libusb/os/windows_common.h
@@ -338,20 +338,36 @@
 	struct winusb_device_priv winusb_priv;
 };
 
-union windows_device_handle_priv {
-	struct usbdk_device_handle_priv usbdk_priv;
-	struct winusb_device_handle_priv winusb_priv;
+struct windows_device_handle_priv {
+	struct list_head active_transfers;
+	union {
+		struct usbdk_device_handle_priv usbdk_priv;
+		struct winusb_device_handle_priv winusb_priv;
+	};
 };
 
 struct windows_transfer_priv {
 	OVERLAPPED overlapped;
 	HANDLE handle;
+	struct list_head list;
 	union {
 		struct usbdk_transfer_priv usbdk_priv;
 		struct winusb_transfer_priv winusb_priv;
 	};
 };
 
+static inline struct usbdk_device_handle_priv *get_usbdk_device_handle_priv(struct libusb_device_handle *dev_handle)
+{
+	struct windows_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	return &handle_priv->usbdk_priv;
+}
+
+static inline struct winusb_device_handle_priv *get_winusb_device_handle_priv(struct libusb_device_handle *dev_handle)
+{
+	struct windows_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	return &handle_priv->winusb_priv;
+}
+
 static inline OVERLAPPED *get_transfer_priv_overlapped(struct usbi_transfer *itransfer)
 {
 	struct windows_transfer_priv *transfer_priv = usbi_get_transfer_priv(itransfer);
diff --git a/libusb/os/windows_usbdk.c b/libusb/os/windows_usbdk.c
index 76aba16..9f52b48 100644
--- a/libusb/os/windows_usbdk.c
+++ b/libusb/os/windows_usbdk.c
@@ -413,7 +413,7 @@
 
 	device_priv->system_handle = usbdk_helper.GetRedirectorSystemHandle(device_priv->redirector_handle);
 
-	if (CreateIoCompletionPort(device_priv->system_handle, priv->completion_port, 0, 0) == NULL) {
+	if (CreateIoCompletionPort(device_priv->system_handle, priv->completion_port, (ULONG_PTR)dev_handle, 0) == NULL) {
 		usbi_err(ctx, "failed to associate handle to I/O completion port: %s", windows_error_str(0));
 		usbdk_helper.StopRedirect(device_priv->redirector_handle);
 		device_priv->system_handle = NULL;
diff --git a/libusb/os/windows_winusb.c b/libusb/os/windows_winusb.c
index ea51038..a370ede 100644
--- a/libusb/os/windows_winusb.c
+++ b/libusb/os/windows_winusb.c
@@ -488,9 +488,9 @@
 /*
  * Open a device and associate the HANDLE with the context's I/O completion port
  */
-static HANDLE windows_open(struct libusb_device *dev, const char *path, DWORD access)
+static HANDLE windows_open(struct libusb_device_handle *dev_handle, const char *path, DWORD access)
 {
-	struct libusb_context *ctx = DEVICE_CTX(dev);
+	struct libusb_context *ctx = HANDLE_CTX(dev_handle);
 	struct windows_context_priv *priv = usbi_get_context_priv(ctx);
 	HANDLE handle;
 
@@ -498,7 +498,7 @@
 	if (handle == INVALID_HANDLE_VALUE)
 		return handle;
 
-	if (CreateIoCompletionPort(handle, priv->completion_port, 0, 0) == NULL) {
+	if (CreateIoCompletionPort(handle, priv->completion_port, (ULONG_PTR)dev_handle, 0) == NULL) {
 		usbi_err(ctx, "failed to associate handle to I/O completion port: %s", windows_error_str(0));
 		CloseHandle(handle);
 		return INVALID_HANDLE_VALUE;
@@ -593,7 +593,7 @@
 static int auto_claim(struct libusb_transfer *transfer, int *interface_number, int api_type)
 {
 	struct winusb_device_handle_priv *handle_priv =
-		usbi_get_device_handle_priv(transfer->dev_handle);
+		get_winusb_device_handle_priv(transfer->dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
 	int current_interface = *interface_number;
 	int r = LIBUSB_SUCCESS;
@@ -640,7 +640,7 @@
 	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
 	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 	libusb_device_handle *dev_handle = transfer->dev_handle;
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
 	int r;
 
 	usbi_mutex_lock(&autoclaim_lock);
@@ -2375,7 +2375,7 @@
 static int winusbx_open(int sub_api, struct libusb_device_handle *dev_handle)
 {
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
 	HANDLE file_handle;
 	int i;
 
@@ -2385,7 +2385,7 @@
 	for (i = 0; i < USB_MAXINTERFACES; i++) {
 		if ((priv->usb_interface[i].path != NULL)
 				&& (priv->usb_interface[i].apib->id == USB_API_WINUSBX)) {
-			file_handle = windows_open(dev_handle->dev, priv->usb_interface[i].path, GENERIC_READ | GENERIC_WRITE);
+			file_handle = windows_open(dev_handle, priv->usb_interface[i].path, GENERIC_READ | GENERIC_WRITE);
 			if (file_handle == INVALID_HANDLE_VALUE) {
 				usbi_err(HANDLE_CTX(dev_handle), "could not open device %s (interface %d): %s", priv->usb_interface[i].path, i, windows_error_str(0));
 				switch (GetLastError()) {
@@ -2407,7 +2407,7 @@
 
 static void winusbx_close(int sub_api, struct libusb_device_handle *dev_handle)
 {
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
 	HANDLE handle;
 	int i;
@@ -2452,7 +2452,7 @@
 
 static int winusbx_configure_endpoints(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface)
 {
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
 	HANDLE winusb_handle = handle_priv->interface_handle[iface].api_handle;
 	UCHAR policy;
@@ -2506,7 +2506,7 @@
 static int winusbx_claim_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface)
 {
 	struct libusb_context *ctx = HANDLE_CTX(dev_handle);
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
 	bool is_using_usbccgp = (priv->apib->id == USB_API_COMPOSITE);
 	HDEVINFO dev_info;
@@ -2557,7 +2557,7 @@
 					*dev_interface_path_guid_start = '\0';
 
 					if (strncmp(dev_interface_path, priv->usb_interface[iface].path, strlen(dev_interface_path)) == 0) {
-						file_handle = windows_open(dev_handle->dev, filter_path, GENERIC_READ | GENERIC_WRITE);
+						file_handle = windows_open(dev_handle, filter_path, GENERIC_READ | GENERIC_WRITE);
 						if (file_handle != INVALID_HANDLE_VALUE) {
 							if (WinUSBX[sub_api].Initialize(file_handle, &winusb_handle)) {
 								// Replace the existing file handle with the working one
@@ -2622,7 +2622,7 @@
 
 static int winusbx_release_interface(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface)
 {
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
 	HANDLE winusb_handle;
 
@@ -2643,7 +2643,7 @@
  */
 static int get_valid_interface(struct libusb_device_handle *dev_handle, int api_id)
 {
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
 	int i;
 
@@ -2667,7 +2667,7 @@
 */
 static int check_valid_interface(struct libusb_device_handle *dev_handle, unsigned short interface, int api_id)
 {
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
 
 	if (interface >= USB_MAXINTERFACES)
@@ -2714,7 +2714,7 @@
 	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
 	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(transfer->dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
 	PWINUSB_SETUP_PACKET setup = (PWINUSB_SETUP_PACKET)transfer->buffer;
 	ULONG size;
 	HANDLE winusb_handle;
@@ -2770,7 +2770,7 @@
 
 static int winusbx_set_interface_altsetting(int sub_api, struct libusb_device_handle *dev_handle, uint8_t iface, uint8_t altsetting)
 {
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
 	HANDLE winusb_handle;
 
@@ -2826,7 +2826,7 @@
 {
 	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(transfer->dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
 	HANDLE winusb_handle;
 	OVERLAPPED *overlapped;
@@ -3016,7 +3016,7 @@
 {
 	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
 	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(transfer->dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
 	HANDLE winusb_handle;
 	OVERLAPPED *overlapped;
@@ -3057,7 +3057,7 @@
 
 static int winusbx_clear_halt(int sub_api, struct libusb_device_handle *dev_handle, unsigned char endpoint)
 {
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
 	HANDLE winusb_handle;
 	int current_interface;
@@ -3084,7 +3084,7 @@
 static int winusbx_cancel_transfer(int sub_api, struct usbi_transfer *itransfer)
 {
 	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(transfer->dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
 	struct winusb_transfer_priv *transfer_priv = get_winusb_transfer_priv(itransfer);
 	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
 	int current_interface = transfer_priv->interface_number;
@@ -3114,7 +3114,7 @@
 // TODO: (post hotplug): see if we can force eject the device and redetect it (reuse hotplug?)
 static int winusbx_reset_device(int sub_api, struct libusb_device_handle *dev_handle)
 {
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
 	HANDLE winusb_handle;
 	int i, j;
@@ -4339,7 +4339,7 @@
 static int composite_submit_bulk_transfer(int sub_api, struct usbi_transfer *itransfer)
 {
 	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(transfer->dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
 	int current_interface;
 
@@ -4360,7 +4360,7 @@
 static int composite_submit_iso_transfer(int sub_api, struct usbi_transfer *itransfer)
 {
 	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(transfer->dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(transfer->dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(transfer->dev_handle->dev);
 	int current_interface;
 
@@ -4380,7 +4380,7 @@
 
 static int composite_clear_halt(int sub_api, struct libusb_device_handle *dev_handle, unsigned char endpoint)
 {
-	struct winusb_device_handle_priv *handle_priv = usbi_get_device_handle_priv(dev_handle);
+	struct winusb_device_handle_priv *handle_priv = get_winusb_device_handle_priv(dev_handle);
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
 	int current_interface;
 
diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index b8e72d6..4227ce9 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11598
+#define LIBUSB_NANO 11599