diff --git a/kernel/ethosu_buffer.c b/kernel/ethosu_buffer.c
index 9033f8b..e9575e7 100644
--- a/kernel/ethosu_buffer.c
+++ b/kernel/ethosu_buffer.c
@@ -120,7 +120,7 @@
 	struct ethosu_buffer *buf = file->private_data;
 	struct device *dev = buf->dev;
 	void __user *udata = (void __user *)arg;
-	int ret = -EINVAL;
+	int ret;
 
 	ret = device_lock_interruptible(dev);
 	if (ret)
@@ -134,8 +134,10 @@
 	case ETHOSU_IOCTL_BUFFER_SET: {
 		struct ethosu_uapi_buffer uapi;
 
-		if (copy_from_user(&uapi, udata, sizeof(uapi)))
+		if (copy_from_user(&uapi, udata, sizeof(uapi))) {
+			ret = -EFAULT;
 			break;
+		}
 
 		dev_info(dev,
 			 "Buffer ioctl: Buffer set. size=%u, offset=%u\n",
@@ -154,8 +156,10 @@
 			 "Buffer ioctl: Buffer get. size=%u, offset=%u\n",
 			 uapi.size, uapi.offset);
 
-		if (copy_to_user(udata, &uapi, sizeof(uapi)))
+		if (copy_to_user(udata, &uapi, sizeof(uapi))) {
+			ret = -EFAULT;
 			break;
+		}
 
 		ret = 0;
 		break;
@@ -163,6 +167,7 @@
 	default: {
 		dev_err(dev, "Invalid ioctl. cmd=%u, arg=%lu",
 			cmd, arg);
+		ret = -ENOIOCTLCMD;
 		break;
 	}
 	}
diff --git a/kernel/ethosu_device.c b/kernel/ethosu_device.c
index 231c6d3..b63d068 100644
--- a/kernel/ethosu_device.c
+++ b/kernel/ethosu_device.c
@@ -242,7 +242,7 @@
 	struct ethosu_device *edev = dev_get_drvdata(&rpdev->dev);
 	struct device *dev = &edev->dev;
 	void __user *udata = (void __user *)arg;
-	int ret = -EINVAL;
+	int ret;
 
 	ret = device_lock_interruptible(dev);
 	if (ret)
@@ -278,8 +278,10 @@
 	case ETHOSU_IOCTL_BUFFER_CREATE: {
 		struct ethosu_uapi_buffer_create uapi;
 
-		if (copy_from_user(&uapi, udata, sizeof(uapi)))
+		if (copy_from_user(&uapi, udata, sizeof(uapi))) {
+			ret = -EFAULT;
 			break;
+		}
 
 		dev_info(dev,
 			 "Device ioctl: Buffer create. capacity=%u",
@@ -291,8 +293,10 @@
 	case ETHOSU_IOCTL_NETWORK_CREATE: {
 		struct ethosu_uapi_network_create uapi;
 
-		if (copy_from_user(&uapi, udata, sizeof(uapi)))
+		if (copy_from_user(&uapi, udata, sizeof(uapi))) {
+			ret = -EFAULT;
 			break;
+		}
 
 		dev_info(dev,
 			 "Device ioctl: Network create. type=%u, fd/index=%u",
@@ -304,6 +308,7 @@
 	default: {
 		dev_err(dev, "Invalid ioctl. cmd=%u, arg=%lu",
 			cmd, arg);
+		ret = -ENOIOCTLCMD;
 		break;
 	}
 	}
diff --git a/kernel/ethosu_inference.c b/kernel/ethosu_inference.c
index 4dcdc0a..60ed954 100644
--- a/kernel/ethosu_inference.c
+++ b/kernel/ethosu_inference.c
@@ -262,6 +262,7 @@
 	default: {
 		dev_err(dev, "Invalid ioctl. cmd=%u, arg=%lu\n",
 			cmd, arg);
+		ret = -ENOIOCTLCMD;
 		break;
 	}
 	}
diff --git a/kernel/ethosu_network.c b/kernel/ethosu_network.c
index 52f6144..6dc0ce4 100644
--- a/kernel/ethosu_network.c
+++ b/kernel/ethosu_network.c
@@ -99,7 +99,7 @@
 	struct ethosu_network *net = file->private_data;
 	struct device *dev = net->dev;
 	void __user *udata = (void __user *)arg;
-	int ret = -EINVAL;
+	int ret;
 
 	ret = device_lock_interruptible(net->dev);
 	if (ret)
@@ -113,8 +113,10 @@
 	case ETHOSU_IOCTL_NETWORK_INFO: {
 		struct ethosu_uapi_network_info uapi;
 
-		if (copy_from_user(&uapi, udata, sizeof(uapi)))
+		if (copy_from_user(&uapi, udata, sizeof(uapi))) {
+			ret = -EFAULT;
 			break;
+		}
 
 		dev_info(dev,
 			 "Network ioctl: Network info. net=0x%pK\n",
@@ -132,8 +134,10 @@
 	case ETHOSU_IOCTL_INFERENCE_CREATE: {
 		struct ethosu_uapi_inference_create uapi;
 
-		if (copy_from_user(&uapi, udata, sizeof(uapi)))
+		if (copy_from_user(&uapi, udata, sizeof(uapi))) {
+			ret = -EFAULT;
 			break;
+		}
 
 		dev_info(dev,
 			 "Network ioctl: Inference. ifm_fd=%u, ofm_fd=%u\n",
@@ -145,6 +149,7 @@
 	default: {
 		dev_err(dev, "Invalid ioctl. cmd=%u, arg=%lu",
 			cmd, arg);
+		ret = -ENOIOCTLCMD;
 		break;
 	}
 	}