diff --git a/library/hmac_drbg.c b/library/hmac_drbg.c
index 1ef819d..dad55ff 100644
--- a/library/hmac_drbg.c
+++ b/library/hmac_drbg.c
@@ -34,7 +34,7 @@
 #if defined(MBEDTLS_HMAC_DRBG_C)
 
 #include "mbedtls/hmac_drbg.h"
-#include "mbedtls/utils.h"
+#include "mbedtls/platform_util.h"
 
 #include <string.h>
 
@@ -334,7 +334,7 @@
     mbedtls_mutex_free( &ctx->mutex );
 #endif
     mbedtls_md_free( &ctx->md_ctx );
-    mbedtls_zeroize( ctx, sizeof( mbedtls_hmac_drbg_context ) );
+    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_hmac_drbg_context ) );
 }
 
 #if defined(MBEDTLS_FS_IO)
@@ -360,7 +360,7 @@
 
 exit:
     fclose( f );
-    mbedtls_zeroize( buf, sizeof( buf ) );
+    mbedtls_platform_zeroize( buf, sizeof( buf ) );
 
     return( ret );
 }
@@ -392,7 +392,7 @@
 
     fclose( f );
 
-    mbedtls_zeroize( buf, sizeof( buf ) );
+    mbedtls_platform_zeroize( buf, sizeof( buf ) );
 
     if( ret != 0 )
         return( ret );