diff --git a/channels/drive/client/drive_file.c b/channels/drive/client/drive_file.c
index 0e62736db..b077da1f8 100644
--- a/channels/drive/client/drive_file.c
+++ b/channels/drive/client/drive_file.c
@@ -578,7 +578,7 @@ BOOL drive_file_set_information(DRIVE_FILE* file, UINT32 FsInformationClass, UIN
 
 			if (file->file_handle == INVALID_HANDLE_VALUE)
 			{
-				WLog_ERR(TAG, "Unable to set file time %s (%d)", file->fullpath, GetLastError());
+				WLog_ERR(TAG, "Unable to set file time %s (%"PRId32")", file->fullpath, GetLastError());
 				return FALSE;
 			}
 
@@ -614,7 +614,7 @@ BOOL drive_file_set_information(DRIVE_FILE* file, UINT32 FsInformationClass, UIN
 
 			if (!SetFileTime(file->file_handle, pftCreationTime, pftLastAccessTime, pftLastWriteTime))
 			{
-				WLog_ERR(TAG, "Unable to set file time %s to %d", file->fullpath);
+				WLog_ERR(TAG, "Unable to set file time to %s", file->fullpath);
 				return FALSE;
 			}
 
@@ -630,7 +630,7 @@ BOOL drive_file_set_information(DRIVE_FILE* file, UINT32 FsInformationClass, UIN
 
 			if (file->file_handle == INVALID_HANDLE_VALUE)
 			{
-				WLog_ERR(TAG, "Unable to truncate %s to %"PRId64" (%d)", file->fullpath, size, GetLastError());
+				WLog_ERR(TAG, "Unable to truncate %s to %"PRId64" (%"PRId32")", file->fullpath, size, GetLastError());
 				return FALSE;
 			}
 
@@ -639,7 +639,7 @@ BOOL drive_file_set_information(DRIVE_FILE* file, UINT32 FsInformationClass, UIN
 			if (SetFilePointer(file->file_handle, liSize.LowPart, &liSize.HighPart,
 			                   FILE_BEGIN) == INVALID_SET_FILE_POINTER)
 			{
-				WLog_ERR(TAG, "Unable to truncate %s to %d (%d)", file->fullpath, size, GetLastError());
+				WLog_ERR(TAG, "Unable to truncate %s to %d (%"PRId32")", file->fullpath, size, GetLastError());
 				return FALSE;
 			}
 
@@ -647,7 +647,7 @@ BOOL drive_file_set_information(DRIVE_FILE* file, UINT32 FsInformationClass, UIN
 
 			if (SetEndOfFile(file->file_handle) == 0)
 			{
-				WLog_ERR(TAG, "Unable to truncate %s to %d (%d)", file->fullpath, size, GetLastError());
+				WLog_ERR(TAG, "Unable to truncate %s to %d (%"PRId32")", file->fullpath, size, GetLastError());
 				return FALSE;
 			}
 
diff --git a/channels/drive/client/drive_main.c b/channels/drive/client/drive_main.c
index 54d7e4421..827244698 100644
--- a/channels/drive/client/drive_main.c
+++ b/channels/drive/client/drive_main.c
@@ -124,7 +124,7 @@ static DWORD drive_map_windows_err(DWORD fs_errno)
 
 		default:
 			rc = STATUS_UNSUCCESSFUL;
-			WLog_ERR(TAG, "Error code not found: %d", fs_errno);
+			WLog_ERR(TAG, "Error code not found: %"PRId32"", fs_errno);
 			break;
 	}
 
diff --git a/winpr/libwinpr/crt/string.c b/winpr/libwinpr/crt/string.c
index b112e2eae..aa70212b7 100644
--- a/winpr/libwinpr/crt/string.c
+++ b/winpr/libwinpr/crt/string.c
@@ -136,6 +136,9 @@ WCHAR* _wcsrchr(const WCHAR* str, WCHAR c)
 	WCHAR *p;
 	WCHAR ch;
 
+	if (!str)
+		return NULL;
+
 	for (p = (WCHAR *) 0; (ch = *str); str++)
 		if (ch == c)
 			p = (WCHAR *) str;
diff --git a/winpr/libwinpr/file/file.c b/winpr/libwinpr/file/file.c
index af4f6f9d3..192ee6e13 100644
--- a/winpr/libwinpr/file/file.c
+++ b/winpr/libwinpr/file/file.c
@@ -105,7 +105,7 @@ static BOOL FileSetEndOfFile(HANDLE hFile)
 		return FALSE;
 
 	size = ftell(pFile->fp);
-	errno = 0;
+
 	if (ftruncate(fileno(pFile->fp), size) < 0)
 	{
 		WLog_ERR(TAG, "ftruncate %s failed with %s [0x%08X]",
@@ -171,10 +171,10 @@ static BOOL FileRead(PVOID Object, LPVOID lpBuffer, DWORD nNumberOfBytesToRead,
 		return FALSE;
 
 	file = (WINPR_FILE *)Object;
-	errno = 0;
+	clearerr(file->fp);
 	io_status = fread(lpBuffer, 1, nNumberOfBytesToRead, file->fp);
 
-	if (io_status == 0 && errno != 0)
+	if (io_status == 0 && ferror(file->fp))
 	{
 		status = FALSE;
 
@@ -212,9 +212,9 @@ static BOOL FileWrite(PVOID Object, LPCVOID lpBuffer, DWORD nNumberOfBytesToWrit
 
 	file = (WINPR_FILE *)Object;
 
-	errno = 0;
+	clearerr(file->fp);
 	io_status = fwrite(lpBuffer, 1, nNumberOfBytesToWrite, file->fp);
-	if (io_status == 0 && errno != 0)
+	if (io_status == 0 && ferror(file->fp))
 	{
 		SetLastError(map_posix_err(errno));
 		return FALSE;
diff --git a/winpr/libwinpr/path/shell.c b/winpr/libwinpr/path/shell.c
index 785197fc9..39a5e5642 100644
--- a/winpr/libwinpr/path/shell.c
+++ b/winpr/libwinpr/path/shell.c
@@ -525,7 +525,7 @@ BOOL PathIsDirectoryEmptyA(LPCSTR pszPath)
 	int empty = 1;
 
 	DIR *dir = opendir(pszPath);
-	if (dir == NULL) //Not a directory or doesn't exist
+	if (dir == NULL) /* Not a directory or doesn't exist */
 		return 1;
 
 	while ((dp = readdir(dir)) != NULL) {