diff --git a/library/pk.c b/library/pk.c
index fc036d2..8bcba58 100644
--- a/library/pk.c
+++ b/library/pk.c
@@ -30,8 +30,6 @@
 #include "polarssl/pk.h"
 #include "polarssl/pk_wrap.h"
 
-#include "polarssl/bignum.h"
-
 #if defined(POLARSSL_RSA_C)
 #include "polarssl/rsa.h"
 #endif
@@ -43,6 +41,7 @@
 #endif
 
 #include <limits.h>
+#include <stdint.h>
 
 /* Implementation that should never be optimized out by the compiler */
 static void polarssl_zeroize( void *v, size_t n ) {
@@ -212,10 +211,10 @@
         int ret;
         const pk_rsassa_pss_options *pss_opts;
 
-#if defined(POLARSSL_HAVE_INT64)
+#if SIZE_MAX > UINT_MAX
         if( md_alg == POLARSSL_MD_NONE && UINT_MAX < hash_len )
             return( POLARSSL_ERR_PK_BAD_INPUT_DATA );
-#endif /* POLARSSL_HAVE_INT64 */
+#endif /* SIZE_MAX > UINT_MAX */
 
         if( options == NULL )
             return( POLARSSL_ERR_PK_BAD_INPUT_DATA );