diff --git a/lib/libwebsockets.c b/lib/libwebsockets.c
index ac502b2f..2ac17629 100644
--- a/lib/libwebsockets.c
+++ b/lib/libwebsockets.c
@@ -786,7 +786,6 @@ lws_ensure_user_space(struct lws *wsi)
 	return 0;
 }
 
-#if LWS_POSIX
 LWS_VISIBLE void lwsl_emit_stderr(int level, const char *line)
 {
 	unsigned long long now;
@@ -806,7 +805,6 @@ LWS_VISIBLE void lwsl_emit_stderr(int level, const char *line)
 
 	fprintf(stderr, "%s%s", buf, line);
 }
-#endif
 
 LWS_VISIBLE void _lws_logv(int filter, const char *format, va_list vl)
 {
diff --git a/lib/libwebsockets.h b/lib/libwebsockets.h
index 195309fe..bfc28e3d 100644
--- a/lib/libwebsockets.h
+++ b/lib/libwebsockets.h
@@ -185,14 +185,15 @@ extern "C" {
 #else /* NOT WIN32 */
 #include <unistd.h>
 
-#define LWS_INVALID_FILE -1
 #define LWS_O_RDONLY O_RDONLY
 
 #ifndef MBED_OPERATORS
 #include <poll.h>
 #include <netdb.h>
+#define LWS_INVALID_FILE -1
 #else
 #define getdtablesize() (20)
+#define LWS_INVALID_FILE NULL
 #endif
 
 #if defined(__GNUC__)
@@ -1362,23 +1363,23 @@ lws_add_http_header_by_name(struct lws_context *context,
 			    unsigned char *end);
 LWS_VISIBLE LWS_EXTERN int
 lws_finalize_http_header(struct lws_context *context,
-			    struct lws *wsi,
-			    unsigned char **p,
-			    unsigned char *end);
+			 struct lws *wsi,
+			 unsigned char **p,
+			 unsigned char *end);
 LWS_VISIBLE LWS_EXTERN int
 lws_add_http_header_by_token(struct lws_context *context,
-			    struct lws *wsi,
-			    enum lws_token_indexes token,
-			    const unsigned char *value,
-			    int length,
-			    unsigned char **p,
-			    unsigned char *end);
+			     struct lws *wsi,
+			     enum lws_token_indexes token,
+			     const unsigned char *value,
+			     int length,
+			     unsigned char **p,
+			     unsigned char *end);
 LWS_VISIBLE LWS_EXTERN int
 lws_add_http_header_content_length(struct lws_context *context,
-			    struct lws *wsi,
-			    unsigned long content_length,
-			    unsigned char **p,
-			    unsigned char *end);
+				   struct lws *wsi,
+				   unsigned long content_length,
+				   unsigned char **p,
+				   unsigned char *end);
 LWS_VISIBLE LWS_EXTERN int
 lws_add_http_header_status(struct lws_context *context, struct lws *wsi,
 			   unsigned int code, unsigned char **p,
diff --git a/lib/lws-plat-mbed3.c b/lib/lws-plat-mbed3.c
index 64a17cbe..6d00fea9 100644
--- a/lib/lws-plat-mbed3.c
+++ b/lib/lws-plat-mbed3.c
@@ -12,12 +12,13 @@ unsigned long long time_in_microseconds(void)
 	return 0;
 }
 
-LWS_VISIBLE int lws_get_random(struct lws_context *context,
-							     void *buf, int len)
+LWS_VISIBLE int lws_get_random(struct lws_context *context, void *buf, int len)
 {
-	(void)context;
 	int n = len;
 	unsigned char *b = (unsigned char *)buf;
+
+	(void)context;
+
 	while (n--)
 		b[n]= rand();
 	return len;
@@ -166,7 +167,7 @@ _lws_plat_file_open(struct lws *wsi, const char *filename,
 	(void)filename;
 	(void)filelen;
 	(void)flags;
-	return -1;
+	return NULL;
 }
 
 static int
@@ -180,7 +181,7 @@ _lws_plat_file_close(struct lws *wsi, lws_filefd_type fd)
 unsigned long
 _lws_plat_file_seek_cur(struct lws *wsi, lws_filefd_type fd, long offset)
 {
-	(void)wsi
+	(void)wsi;
 	(void)fd;
 	(void)offset;
 
@@ -189,7 +190,7 @@ _lws_plat_file_seek_cur(struct lws *wsi, lws_filefd_type fd, long offset)
 
 static int
 _lws_plat_file_read(struct lws *wsi, lws_filefd_type fd, unsigned long *amount,
-		    unsigned char* buf, unsigned long* len)
+		    unsigned char *buf, unsigned long len)
 {
 	(void)wsi;
 	(void)amount;
@@ -202,7 +203,7 @@ _lws_plat_file_read(struct lws *wsi, lws_filefd_type fd, unsigned long *amount,
 
 static int
 _lws_plat_file_write(struct lws *wsi, lws_filefd_type fd, unsigned long *amount,
-		     unsigned char* buf, unsigned long len)
+		     unsigned char *buf, unsigned long len)
 {
 	(void)wsi;
 	(void)amount;
@@ -217,6 +218,8 @@ LWS_VISIBLE int
 lws_plat_init(struct lws_context *context,
 	      struct lws_context_creation_info *info)
 {
+	(void)info;
+
 	context->fops.open	= _lws_plat_file_open;
 	context->fops.close	= _lws_plat_file_close;
 	context->fops.seek_cur	= _lws_plat_file_seek_cur;
diff --git a/lib/lws-plat-mbed3.cpp b/lib/lws-plat-mbed3.cpp
index 826cb71b..70a76e0d 100644
--- a/lib/lws-plat-mbed3.cpp
+++ b/lib/lws-plat-mbed3.cpp
@@ -216,7 +216,7 @@ void lws_conn_listener::onIncoming(TCPListener *tl, void *impl)
 }
 
 extern "C" LWS_VISIBLE struct lws *
-wsi_from_fd(struct lws_context *context, lws_sockfd_type fd)
+wsi_from_fd(const struct lws_context *context, lws_sockfd_type fd)
 {
 	lws_conn *conn = (lws_conn *)fd;
 	(void)context;
diff --git a/lib/private-libwebsockets.h b/lib/private-libwebsockets.h
index 8e53c1c3..f6f0f267 100644
--- a/lib/private-libwebsockets.h
+++ b/lib/private-libwebsockets.h
@@ -950,7 +950,7 @@ lws_b64_selftest(void);
 
 #if defined(_WIN32) || defined(MBED_OPERATORS)
 LWS_EXTERN struct lws *
-wsi_from_fd(struct lws_context *context, lws_sockfd_type fd);
+wsi_from_fd(const struct lws_context *context, lws_sockfd_type fd);
 
 LWS_EXTERN int
 insert_wsi(struct lws_context *context, struct lws *wsi);