diff --git a/libusb/core.c b/libusb/core.c
index 85d62e4..7ffec1f 100644
--- a/libusb/core.c
+++ b/libusb/core.c
@@ -746,10 +746,10 @@
 	if (num_configurations > USB_MAXCONFIG) {
 		usbi_err(DEVICE_CTX(dev), "too many configurations");
 		return LIBUSB_ERROR_IO;
-	} else if (0 == num_configurations)
+	} else if (0 == num_configurations) {
 		usbi_dbg("zero configurations, maybe an unauthorized device");
+	}
 
-	dev->num_configurations = num_configurations;
 	return 0;
 }
 
@@ -1636,6 +1636,8 @@
 	int configuration)
 {
 	usbi_dbg("configuration %d", configuration);
+	if (configuration < -1 || configuration > UINT8_MAX)
+		return LIBUSB_ERROR_INVALID_PARAM;
 	return usbi_backend.set_configuration(dev_handle, configuration);
 }
 
@@ -1673,7 +1675,7 @@
 	int r = 0;
 
 	usbi_dbg("interface %d", interface_number);
-	if (interface_number >= USB_MAXINTERFACES)
+	if (interface_number < 0 || interface_number >= USB_MAXINTERFACES)
 		return LIBUSB_ERROR_INVALID_PARAM;
 
 	if (!dev_handle->dev->attached)
@@ -1717,7 +1719,7 @@
 	int r;
 
 	usbi_dbg("interface %d", interface_number);
-	if (interface_number >= USB_MAXINTERFACES)
+	if (interface_number < 0 || interface_number >= USB_MAXINTERFACES)
 		return LIBUSB_ERROR_INVALID_PARAM;
 
 	usbi_mutex_lock(&dev_handle->lock);
@@ -1761,7 +1763,9 @@
 {
 	usbi_dbg("interface %d altsetting %d",
 		interface_number, alternate_setting);
-	if (interface_number >= USB_MAXINTERFACES)
+	if (interface_number < 0 || interface_number >= USB_MAXINTERFACES)
+		return LIBUSB_ERROR_INVALID_PARAM;
+	if (alternate_setting < 0 || alternate_setting > UINT8_MAX)
 		return LIBUSB_ERROR_INVALID_PARAM;
 
 	usbi_mutex_lock(&dev_handle->lock);
@@ -1858,7 +1862,10 @@
 int API_EXPORTED libusb_alloc_streams(libusb_device_handle *dev_handle,
 	uint32_t num_streams, unsigned char *endpoints, int num_endpoints)
 {
-	usbi_dbg("streams %u eps %d", (unsigned) num_streams, num_endpoints);
+	usbi_dbg("streams %u eps %d", (unsigned)num_streams, num_endpoints);
+
+	if (!num_streams || !endpoints || num_endpoints <= 0)
+		return LIBUSB_ERROR_INVALID_PARAM;
 
 	if (!dev_handle->dev->attached)
 		return LIBUSB_ERROR_NO_DEVICE;
@@ -1887,6 +1894,9 @@
 {
 	usbi_dbg("eps %d", num_endpoints);
 
+	if (!endpoints || num_endpoints <= 0)
+		return LIBUSB_ERROR_INVALID_PARAM;
+
 	if (!dev_handle->dev->attached)
 		return LIBUSB_ERROR_NO_DEVICE;
 
@@ -1973,6 +1983,9 @@
 {
 	usbi_dbg("interface %d", interface_number);
 
+	if (interface_number < 0 || interface_number >= USB_MAXINTERFACES)
+		return LIBUSB_ERROR_INVALID_PARAM;
+
 	if (!dev_handle->dev->attached)
 		return LIBUSB_ERROR_NO_DEVICE;
 
@@ -2008,6 +2021,9 @@
 {
 	usbi_dbg("interface %d", interface_number);
 
+	if (interface_number < 0 || interface_number >= USB_MAXINTERFACES)
+		return LIBUSB_ERROR_INVALID_PARAM;
+
 	if (!dev_handle->dev->attached)
 		return LIBUSB_ERROR_NO_DEVICE;
 
@@ -2042,6 +2058,9 @@
 {
 	usbi_dbg("interface %d", interface_number);
 
+	if (interface_number < 0 || interface_number >= USB_MAXINTERFACES)
+		return LIBUSB_ERROR_INVALID_PARAM;
+
 	if (!dev_handle->dev->attached)
 		return LIBUSB_ERROR_NO_DEVICE;
 
diff --git a/libusb/descriptor.c b/libusb/descriptor.c
index 4c7733d..44237dd 100644
--- a/libusb/descriptor.c
+++ b/libusb/descriptor.c
@@ -617,7 +617,7 @@
 	int r;
 
 	usbi_dbg("index %d", config_index);
-	if (config_index >= dev->num_configurations)
+	if (config_index >= dev->device_descriptor.bNumConfigurations)
 		return LIBUSB_ERROR_NOT_FOUND;
 
 	r = usbi_backend.get_config_descriptor(dev, config_index, tmp,
@@ -655,7 +655,7 @@
 	uint8_t i;
 
 	usbi_dbg("value %d", bConfigurationValue);
-	for (i = 0; i < dev->num_configurations; i++) {
+	for (i = 0; i < dev->device_descriptor.bNumConfigurations; i++) {
 		unsigned char tmp[6];
 		int host_endian;
 		int r = usbi_backend.get_config_descriptor(dev, i, tmp, sizeof(tmp),
diff --git a/libusb/io.c b/libusb/io.c
index b843d4a..09ccc83 100644
--- a/libusb/io.c
+++ b/libusb/io.c
@@ -1261,6 +1261,8 @@
 	struct libusb_transfer *transfer;
 
 	assert(iso_packets >= 0);
+	if (iso_packets < 0)
+		return NULL;
 
 	priv_size = PTR_ALIGN(usbi_backend.transfer_priv_size);
 	alloc_size = priv_size
diff --git a/libusb/libusbi.h b/libusb/libusbi.h
index faaeff3..1fdfc84 100644
--- a/libusb/libusbi.h
+++ b/libusb/libusbi.h
@@ -429,12 +429,11 @@
 	int refcnt;
 
 	struct libusb_context *ctx;
+	struct libusb_device *parent_dev;
 
 	uint8_t bus_number;
 	uint8_t port_number;
-	struct libusb_device* parent_dev;
 	uint8_t device_address;
-	uint8_t num_configurations;
 	enum libusb_speed speed;
 
 	struct list_head list;
diff --git a/libusb/os/haiku_usb_raw.cpp b/libusb/os/haiku_usb_raw.cpp
index 3162371..63efc17 100644
--- a/libusb/os/haiku_usb_raw.cpp
+++ b/libusb/os/haiku_usb_raw.cpp
@@ -97,7 +97,7 @@
 	const usb_configuration_descriptor *config = dev->ConfigurationDescriptor(config_index);
 	if (config == NULL) {
 		usbi_err(DEVICE_CTX(device), "failed getting configuration descriptor");
-		return LIBUSB_ERROR_INVALID_PARAM;
+		return LIBUSB_ERROR_IO;
 	}
 	if (len > config->total_length) {
 		len = config->total_length;
diff --git a/libusb/os/sunos_usb.c b/libusb/os/sunos_usb.c
index 8d0c812..cd32f8b 100644
--- a/libusb/os/sunos_usb.c
+++ b/libusb/os/sunos_usb.c
@@ -1109,8 +1109,8 @@
 	if (dpriv->ugenpath == NULL)
 		return (LIBUSB_ERROR_NOT_SUPPORTED);
 
-	if (config < 1 || config > dpriv->dev_descr.bNumConfigurations)
-		return (LIBUSB_ERROR_INVALID_PARAM);
+	if (config < 1)
+		return (LIBUSB_ERROR_NOT_SUPPORTED);
 
 	dpriv->cfgvalue = config;
 	hpriv->config_index = config - 1;
@@ -1122,9 +1122,6 @@
 sunos_claim_interface(struct libusb_device_handle *handle, int iface)
 {
 	usbi_dbg("iface %d", iface);
-	if (iface < 0) {
-		return (LIBUSB_ERROR_INVALID_PARAM);
-	}
 
 	return (LIBUSB_SUCCESS);
 }
@@ -1135,9 +1132,6 @@
 	sunos_dev_handle_priv_t *hpriv = usbi_get_device_handle_priv(handle);
 
 	usbi_dbg("iface %d", iface);
-	if (iface < 0) {
-		return (LIBUSB_ERROR_INVALID_PARAM);
-	}
 
 	/* XXX: can we release it? */
 	hpriv->altsetting[iface] = 0;
@@ -1154,9 +1148,6 @@
 
 	usbi_dbg("iface %d, setting %d", iface, altsetting);
 
-	if (iface < 0 || altsetting < 0) {
-		return (LIBUSB_ERROR_INVALID_PARAM);
-	}
 	if (dpriv->ugenpath == NULL)
 		return (LIBUSB_ERROR_NOT_FOUND);
 
diff --git a/libusb/os/windows_usbdk.c b/libusb/os/windows_usbdk.c
index 9c3e8fd..bb370ca 100644
--- a/libusb/os/windows_usbdk.c
+++ b/libusb/os/windows_usbdk.c
@@ -286,7 +286,6 @@
 	// Addresses in libusb are 1-based
 	dev->device_address = (uint8_t)(info->Port + 1);
 
-	dev->num_configurations = info->DeviceDescriptor.bNumConfigurations;
 	memcpy(&dev->device_descriptor, &info->DeviceDescriptor, LIBUSB_DT_DEVICE_SIZE);
 
 	switch (info->Speed) {
@@ -373,9 +372,6 @@
 	PUSB_CONFIGURATION_DESCRIPTOR config_header;
 	size_t size;
 
-	if (config_index >= dev->num_configurations)
-		return LIBUSB_ERROR_INVALID_PARAM;
-
 	config_header = (PUSB_CONFIGURATION_DESCRIPTOR)priv->config_descriptors[config_index];
 
 	size = min(config_header->wTotalLength, len);
@@ -390,7 +386,7 @@
 	PUSB_CONFIGURATION_DESCRIPTOR config_header;
 	uint8_t index;
 
-	for (index = 0; index < dev->num_configurations; index++) {
+	for (index = 0; index < dev->device_descriptor.bNumConfigurations; index++) {
 		config_header = priv->config_descriptors[index];
 		if (config_header->bConfigurationValue == bConfigurationValue) {
 			*buffer = (unsigned char *)priv->config_descriptors[index];
diff --git a/libusb/os/windows_winusb.c b/libusb/os/windows_winusb.c
index ef6fbd2..245df90 100644
--- a/libusb/os/windows_winusb.c
+++ b/libusb/os/windows_winusb.c
@@ -681,27 +681,28 @@
 	struct libusb_context *ctx = DEVICE_CTX(dev);
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev);
 	DWORD size, ret_size;
-	uint8_t i;
+	uint8_t i, num_configurations;
 
 	USB_CONFIGURATION_DESCRIPTOR_SHORT cd_buf_short; // dummy request
 	PUSB_DESCRIPTOR_REQUEST cd_buf_actual = NULL;    // actual request
 	PUSB_CONFIGURATION_DESCRIPTOR cd_data;
 
-	if (dev->num_configurations == 0)
+	num_configurations = priv->dev_descriptor.bNumConfigurations;
+	if (num_configurations == 0)
 		return;
 
 	assert(sizeof(USB_DESCRIPTOR_REQUEST) == USB_DESCRIPTOR_REQUEST_SIZE);
 
-	priv->config_descriptor = calloc(dev->num_configurations, sizeof(PUSB_CONFIGURATION_DESCRIPTOR));
+	priv->config_descriptor = calloc(num_configurations, sizeof(PUSB_CONFIGURATION_DESCRIPTOR));
 	if (priv->config_descriptor == NULL) {
 		usbi_err(ctx, "could not allocate configuration descriptor array for '%s'", priv->dev_id);
 		return;
 	}
 
-	for (i = 0; i <= dev->num_configurations; i++) {
+	for (i = 0; i <= num_configurations; i++) {
 		safe_free(cd_buf_actual);
 
-		if (i == dev->num_configurations)
+		if (i == num_configurations)
 			break;
 
 		size = sizeof(cd_buf_short);
@@ -860,13 +861,12 @@
 			}
 
 			memcpy(&priv->dev_descriptor, &(conn_info.DeviceDescriptor), sizeof(USB_DEVICE_DESCRIPTOR));
-			dev->num_configurations = conn_info.DeviceDescriptor.bNumConfigurations;
 			priv->active_config = conn_info.CurrentConfigurationValue;
 			if (priv->active_config == 0) {
 				usbi_dbg("0x%x:0x%x found %u configurations (not configured)",
 					priv->dev_descriptor.idVendor,
 					priv->dev_descriptor.idProduct,
-					dev->num_configurations);
+					priv->dev_descriptor.bNumConfigurations);
 				SleepEx(50, TRUE);
 			}
 		} while (priv->active_config == 0 && --ginfotimeout >= 0);
@@ -876,10 +876,10 @@
 				"forcing current configuration to 1",
 				priv->dev_descriptor.idVendor,
 				priv->dev_descriptor.idProduct,
-				dev->num_configurations);
+				priv->dev_descriptor.bNumConfigurations);
 			priv->active_config = 1;
 		} else {
-			usbi_dbg("found %u configurations (current config: %u)", dev->num_configurations, priv->active_config);
+			usbi_dbg("found %u configurations (current config: %u)", priv->dev_descriptor.bNumConfigurations, priv->active_config);
 		}
 
 		// Cache as many config descriptors as we can
@@ -957,7 +957,6 @@
 		usbi_dbg("assigning HCD '%s' bus number %u", dev_id, bus_number);
 		priv = usbi_get_device_priv(dev);
 		dev->bus_number = bus_number;
-		dev->num_configurations = 1;
 		priv->dev_descriptor.bLength = LIBUSB_DT_DEVICE_SIZE;
 		priv->dev_descriptor.bDescriptorType = LIBUSB_DT_DEVICE;
 		priv->dev_descriptor.bDeviceClass = LIBUSB_CLASS_HUB;
@@ -1543,10 +1542,6 @@
 	PUSB_CONFIGURATION_DESCRIPTOR config_header;
 	size_t size;
 
-	// config index is zero based
-	if (config_index >= dev->num_configurations)
-		return LIBUSB_ERROR_INVALID_PARAM;
-
 	if ((priv->config_descriptor == NULL) || (priv->config_descriptor[config_index] == NULL))
 		return LIBUSB_ERROR_NOT_FOUND;
 
@@ -1567,7 +1562,7 @@
 	if (priv->config_descriptor == NULL)
 		return LIBUSB_ERROR_NOT_FOUND;
 
-	for (index = 0; index < dev->num_configurations; index++) {
+	for (index = 0; index < dev->device_descriptor.bNumConfigurations; index++) {
 		config_header = priv->config_descriptor[index];
 		if (config_header == NULL)
 			continue;
@@ -1641,9 +1636,6 @@
 	struct winusb_device_priv *priv = usbi_get_device_priv(dev_handle->dev);
 	int r = LIBUSB_SUCCESS;
 
-	if (config >= USB_MAXCONFIG)
-		return LIBUSB_ERROR_INVALID_PARAM;
-
 	r = libusb_control_transfer(dev_handle, LIBUSB_ENDPOINT_OUT |
 		LIBUSB_REQUEST_TYPE_STANDARD | LIBUSB_RECIPIENT_DEVICE,
 		LIBUSB_REQUEST_SET_CONFIGURATION, (uint16_t)config,
@@ -2478,9 +2470,6 @@
 
 	CHECK_WINUSBX_AVAILABLE(sub_api);
 
-	if (altsetting > 255)
-		return LIBUSB_ERROR_INVALID_PARAM;
-
 	winusb_handle = handle_priv->interface_handle[iface].api_handle;
 	if (!HANDLE_VALID(winusb_handle)) {
 		usbi_err(HANDLE_CTX(dev_handle), "interface must be claimed first");
@@ -3592,9 +3581,6 @@
 
 	CHECK_HID_AVAILABLE;
 
-	if (altsetting > 255)
-		return LIBUSB_ERROR_INVALID_PARAM;
-
 	if (altsetting != 0) {
 		usbi_err(HANDLE_CTX(dev_handle), "set interface altsetting not supported for altsetting >0");
 		return LIBUSB_ERROR_NOT_SUPPORTED;
@@ -3615,7 +3601,7 @@
 	OVERLAPPED *overlapped;
 	int current_interface, config;
 	size_t size;
-	int r = LIBUSB_ERROR_INVALID_PARAM;
+	int r;
 
 	UNUSED(sub_api);
 	CHECK_HID_AVAILABLE;
diff --git a/libusb/os/windows_winusb.h b/libusb/os/windows_winusb.h
index c8d3f15..0340fe7 100644
--- a/libusb/os/windows_winusb.h
+++ b/libusb/os/windows_winusb.h
@@ -220,8 +220,8 @@
 
 	free(priv->dev_id);
 	free(priv->path);
-	if ((dev->num_configurations > 0) && (priv->config_descriptor != NULL)) {
-		for (i = 0; i < dev->num_configurations; i++) {
+	if ((priv->dev_descriptor.bNumConfigurations > 0) && (priv->config_descriptor != NULL)) {
+		for (i = 0; i < priv->dev_descriptor.bNumConfigurations; i++) {
 			if (priv->config_descriptor[i] == NULL)
 				continue;
 			free((UCHAR *)priv->config_descriptor[i] - USB_DESCRIPTOR_REQUEST_SIZE);
diff --git a/libusb/version_nano.h b/libusb/version_nano.h
index 3804599..a744f2f 100644
--- a/libusb/version_nano.h
+++ b/libusb/version_nano.h
@@ -1 +1 @@
-#define LIBUSB_NANO 11464
+#define LIBUSB_NANO 11465