diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index ff532a0..ae6d62f 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -33,6 +33,7 @@
 #if defined(MBEDTLS_CTR_DRBG_C)
 
 #include "mbedtls/ctr_drbg.h"
+#include "mbedtls/utils.h"
 
 #include <string.h>
 
@@ -49,11 +50,6 @@
 #endif /* MBEDTLS_PLATFORM_C */
 #endif /* MBEDTLS_SELF_TEST */
 
-/* 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;
-}
-
 /*
  * CTR_DRBG context initialization
  */