Just use stdint.h even with MSVC
diff --git a/include/mbedtls/bignum.h b/include/mbedtls/bignum.h
index 88fc86e..84f47e1 100644
--- a/include/mbedtls/bignum.h
+++ b/include/mbedtls/bignum.h
@@ -31,21 +31,12 @@
#endif
#include <stddef.h>
+#include <stdint.h>
#if defined(MBEDTLS_FS_IO)
#include <stdio.h>
#endif
-#if defined(_MSC_VER) && !defined(EFIX64) && !defined(EFI32)
-#include <basetsd.h>
-typedef INT32 int32_t;
-typedef INT64 int64_t;
-typedef UINT32 uint32_t;
-typedef UINT64 uint64_t;
-#else
-#include <inttypes.h>
-#endif /* _MSC_VER && !EFIX64 && !EFI32 */
-
#define MBEDTLS_ERR_MPI_FILE_IO_ERROR -0x0002 /**< An error occurred while reading from or writing to a file. */
#define MBEDTLS_ERR_MPI_BAD_INPUT_DATA -0x0004 /**< Bad input parameters to function. */
#define MBEDTLS_ERR_MPI_INVALID_CHARACTER -0x0006 /**< There is an invalid character in the digit string. */