diff --git a/library/sha256.c b/library/sha256.c
index f39bcba..c92f280 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -33,6 +33,7 @@
 #if defined(MBEDTLS_SHA256_C)
 
 #include "mbedtls/sha256.h"
+#include "mbedtls/utils.h"
 
 #include <string.h>
 
@@ -50,11 +51,6 @@
 
 #if !defined(MBEDTLS_SHA256_ALT)
 
-/* Implementation that should never be optimized out by the compiler */
-static void mbedtls_zeroize( void *v, size_t n ) {
-    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
-}
-
 /*
  * 32-bit integer manipulation macros (big endian)
  */