diff --git a/library/pk.c b/library/pk.c
index 8d13bc5..b52c73f 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -29,8 +29,6 @@
 #include "mbedtls/pk.h"
 #include "mbedtls/pk_internal.h"
 
-#include "mbedtls/bignum.h"
-
 #if defined(MBEDTLS_RSA_C)
 #include "mbedtls/rsa.h"
 #endif
@@ -42,6 +40,7 @@
 #endif
 
 #include <limits.h>
+#include <stdint.h>
 
 /* Implementation that should never be optimized out by the compiler */
 static void mbedtls_zeroize( void *v, size_t n ) {
@@ -213,10 +212,10 @@
         int ret;
         const mbedtls_pk_rsassa_pss_options *pss_opts;
 
-#if defined(MBEDTLS_HAVE_INT64)
+#if SIZE_MAX > UINT_MAX
         if( md_alg == MBEDTLS_MD_NONE && UINT_MAX < hash_len )
             return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
-#endif /* MBEDTLS_HAVE_INT64 */
+#endif /* SIZE_MAX > UINT_MAX */
 
         if( options == NULL )
             return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );