diff --git a/drivers/io/io_semihosting.c b/drivers/io/io_semihosting.c
index a37693d..3c92c6d 100644
--- a/drivers/io/io_semihosting.c
+++ b/drivers/io/io_semihosting.c
@@ -44,23 +44,23 @@
 
 /* Semi-hosting functions, device info and handle */
 
-static int sh_dev_open(void *spec, io_dev_info_t **dev_info);
-static int sh_file_open(io_dev_info_t *dev_info, const void *spec,
+static int sh_dev_open(const uintptr_t dev_spec, io_dev_info_t **dev_info);
+static int sh_file_open(io_dev_info_t *dev_info, const uintptr_t spec,
 		io_entity_t *entity);
 static int sh_file_seek(io_entity_t *entity, int mode, ssize_t offset);
 static int sh_file_len(io_entity_t *entity, size_t *length);
-static int sh_file_read(io_entity_t *entity, void *buffer, size_t length,
+static int sh_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
 		size_t *length_read);
-static int sh_file_write(io_entity_t *entity, const void *buffer,
+static int sh_file_write(io_entity_t *entity, const uintptr_t buffer,
 		size_t length, size_t *length_written);
 static int sh_file_close(io_entity_t *entity);
 
-static struct io_dev_connector sh_dev_connector = {
+static const io_dev_connector_t sh_dev_connector = {
 	.dev_open = sh_dev_open
 };
 
 
-static struct io_dev_funcs sh_dev_funcs = {
+static const io_dev_funcs_t sh_dev_funcs = {
 	.type = device_type_sh,
 	.open = sh_file_open,
 	.seek = sh_file_seek,
@@ -73,29 +73,31 @@
 };
 
 
-static struct io_dev_info sh_dev_info = {
+/* No state associated with this device so structure can be const */
+static const io_dev_info_t sh_dev_info = {
 	.funcs = &sh_dev_funcs,
 	.info = (uintptr_t)NULL
 };
 
 
 /* Open a connection to the semi-hosting device */
-static int sh_dev_open(void *spec __unused, io_dev_info_t **dev_info)
+static int sh_dev_open(const uintptr_t dev_spec __unused,
+		io_dev_info_t **dev_info)
 {
 	int result = IO_SUCCESS;
 	assert(dev_info != NULL);
-	*dev_info = &sh_dev_info;
+	*dev_info = (io_dev_info_t *)&sh_dev_info; /* cast away const */
 	return result;
 }
 
 
 /* Open a file on the semi-hosting device */
 static int sh_file_open(io_dev_info_t *dev_info __attribute__((unused)),
-		const void *spec, io_entity_t *entity)
+		const uintptr_t spec, io_entity_t *entity)
 {
 	int result = IO_FAIL;
 	long sh_result = -1;
-	const io_file_spec_t *file_spec = (io_file_spec_t *)spec;
+	const io_file_spec_t *file_spec = (const io_file_spec_t *)spec;
 
 	assert(file_spec != NULL);
 	assert(entity != NULL);
@@ -151,7 +153,7 @@
 
 
 /* Read data from a file on the semi-hosting device */
-static int sh_file_read(io_entity_t *entity, void *buffer, size_t length,
+static int sh_file_read(io_entity_t *entity, uintptr_t buffer, size_t length,
 		size_t *length_read)
 {
 	int result = IO_FAIL;
@@ -160,7 +162,7 @@
 	long file_handle;
 
 	assert(entity != NULL);
-	assert(buffer != NULL);
+	assert(buffer != (uintptr_t)NULL);
 	assert(length_read != NULL);
 
 	file_handle = (long)entity->info;
@@ -178,7 +180,7 @@
 
 
 /* Write data to a file on the semi-hosting device */
-static int sh_file_write(io_entity_t *entity, const void *buffer,
+static int sh_file_write(io_entity_t *entity, const uintptr_t buffer,
 		size_t length, size_t *length_written)
 {
 	int result = IO_FAIL;
@@ -187,7 +189,7 @@
 	size_t bytes = length;
 
 	assert(entity != NULL);
-	assert(buffer != NULL);
+	assert(buffer != (uintptr_t)NULL);
 	assert(length_written != NULL);
 
 	file_handle = (long)entity->info;
@@ -226,7 +228,7 @@
 /* Exported functions */
 
 /* Register the semi-hosting driver with the IO abstraction */
-int register_io_dev_sh(io_dev_connector_t **dev_con)
+int register_io_dev_sh(const io_dev_connector_t **dev_con)
 {
 	int result = IO_FAIL;
 	assert(dev_con != NULL);