diff --git a/README b/README
index e0ace97..50cb7b2 100644
--- a/README
+++ b/README
@@ -61,9 +61,8 @@ API
 The API is simple, and designed to be a minimal wrapper around the serial port
 support in each OS.
 
-Most functions take a pointer to a struct sp_port, which represents an open
-port. This structure should be allocated by the user and is populated by
-sp_open(). It can be freed safely after sp_close().
+Most functions take a pointer to a struct sp_port, which represents an serial
+port. This structure is obtained from the array returned by sp_list_ports().
 
 All functions can return only three possible error values. SP_ERR_ARG indicates
 the function was called with invalid arguments. SP_ERR_FAIL indicates that the
@@ -83,27 +82,26 @@ The available functions are as follows:
 Enumeration
 -----------
 
-char **sp_list_ports();
+struct sp_port **sp_list_ports();
 
  Lists the serial ports available on the system. The value returned is an array
- of port names as C strings, terminated by a NULL. It should be freed after use
- by calling sp_free_port_list().
+ of pointers to sp_port structures, terminated by a NULL. It should be freed after
+ use by calling sp_free_port_list().
 
-void sp_free_port_list(char **list);
+void sp_free_port_list(struct sp_port **list);
 
  Frees the data structure returned by sp_list_ports().
 
 Opening and closing ports
 -------------------------
 
-int sp_open(struct sp_port *port, char *portname, int flags);
+int sp_open(struct sp_port *port, int flags);
 
  Opens the specified serial port.
 
  Parameters:
 
-  port:      Pointer to empty port structure, allocated by caller.
-  portname:  Name of port to open.
+  port:      Pointer to port structure.
   flags:     Flags to use when opening the serial port. Possible
              flags are: SP_MODE_RDWR, SP_MODE_RDONLY, and SP_MODE_NONBLOCK.
 
diff --git a/serialport.c b/serialport.c
index ce306fd..c2f6f62 100644
--- a/serialport.c
+++ b/serialport.c
@@ -45,17 +45,34 @@
 
 #include "serialport.h"
 
-static char **sp_list_append(char **list, void *data, size_t len)
+static struct sp_port *sp_port_new(char *portname, size_t len)
+{
+	struct sp_port *port;
+
+	if (!(port = malloc(sizeof(struct sp_port))))
+		return NULL;
+
+	if (!(port->name = malloc(len)))
+	{
+		free(port);
+		return NULL;
+	}
+
+	memcpy(port->name, portname, len);
+
+	return port;
+}
+
+static struct sp_port **sp_list_append(struct sp_port **list, char *portname, size_t len)
 {
 	void *tmp;
 	unsigned int count;
 	for (count = 0; list[count]; count++);
-	if (!(tmp = realloc(list, sizeof(char *) * (count + 2))))
+	if (!(tmp = realloc(list, sizeof(struct sp_port *) * (count + 2))))
 		goto fail;
 	list = tmp;
-	if (!(list[count] = malloc(len)))
+	if (!(list[count] = sp_port_new(portname, len)))
 		goto fail;
-	memcpy(list[count], data, len);
 	list[count + 1] = NULL;
 	return list;
 fail:
@@ -68,11 +85,11 @@ fail:
  *
  * @return A null-terminated array of port name strings.
  */
-char **sp_list_ports(void)
+struct sp_port **sp_list_ports(void)
 {
-	char **list;
+	struct sp_port **list;
 
-	if (!(list = malloc(sizeof(char *))))
+	if (!(list = malloc(sizeof(struct sp_port **))))
 		return NULL;
 
 	list[0] = NULL;
@@ -224,7 +241,7 @@ out:
 /**
  * Free a port list returned by sp_list_ports.
  */
-void sp_free_port_list(char **list)
+void sp_free_port_list(struct sp_port **list)
 {
 	unsigned int i;
 	for (i = 0; list[i]; i++)
@@ -259,16 +276,11 @@ static int sp_validate_port(struct sp_port *port)
  * @return SP_OK on success, SP_ERR_FAIL on failure,
  *         or SP_ERR_ARG if an invalid port or name is passed.
  */
-int sp_open(struct sp_port *port, char *portname, int flags)
+int sp_open(struct sp_port *port, int flags)
 {
 	if (!port)
 		return SP_ERR_ARG;
 
-	if (!portname)
-		return SP_ERR_ARG;
-
-	port->name = portname;
-
 #ifdef _WIN32
 	DWORD desired_access = 0, flags_and_attributes = 0;
 	/* Map 'flags' to the OS-specific settings. */
diff --git a/serialport.h b/serialport.h
index 3d6410e..8c42720 100644
--- a/serialport.h
+++ b/serialport.h
@@ -79,9 +79,9 @@ enum {
 	SP_FLOW_SOFTWARE = 2
 };
 
-char **sp_list_ports(void);
-void sp_free_port_list(char **ports);
-int sp_open(struct sp_port *port, char *portname, int flags);
+struct sp_port **sp_list_ports(void);
+void sp_free_port_list(struct sp_port **ports);
+int sp_open(struct sp_port *port, int flags);
 int sp_close(struct sp_port *port);
 int sp_flush(struct sp_port *port);
 int sp_write(struct sp_port *port, const void *buf, size_t count);