diff --git a/crypto/hkdf/hkdf.c b/crypto/hkdf/hkdf.c
index f21cb42..ae43b69 100644
--- a/crypto/hkdf/hkdf.c
+++ b/crypto/hkdf/hkdf.c
@@ -20,6 +20,8 @@
 #include <openssl/err.h>
 #include <openssl/hmac.h>
 
+#include "../internal.h"
+
 
 int HKDF(uint8_t *out_key, size_t out_len, const EVP_MD *digest,
          const uint8_t *secret, size_t secret_len, const uint8_t *salt,
@@ -95,7 +97,7 @@
     if (done + todo > out_len) {
       todo = out_len - done;
     }
-    memcpy(out_key + done, previous, todo);
+    OPENSSL_memcpy(out_key + done, previous, todo);
     done += todo;
   }
 
diff --git a/crypto/hkdf/hkdf_test.c b/crypto/hkdf/hkdf_test.c
index 4499cc0..d9b50fa 100644
--- a/crypto/hkdf/hkdf_test.c
+++ b/crypto/hkdf/hkdf_test.c
@@ -262,7 +262,7 @@
       return 1;
     }
     if (prk_len != test->prk_len ||
-        memcmp(prk, test->prk, test->prk_len) != 0) {
+        OPENSSL_memcmp(prk, test->prk, test->prk_len) != 0) {
       fprintf(stderr, "%zu: Resulting PRK does not match test vector\n", i);
       return 1;
     }
@@ -272,7 +272,7 @@
       ERR_print_errors_fp(stderr);
       return 1;
     }
-    if (memcmp(buf, test->out, test->out_len) != 0) {
+    if (OPENSSL_memcmp(buf, test->out, test->out_len) != 0) {
       fprintf(stderr,
               "%zu: Resulting key material does not match test vector\n", i);
       return 1;
@@ -284,7 +284,7 @@
       ERR_print_errors_fp(stderr);
       return 1;
     }
-    if (memcmp(buf, test->out, test->out_len) != 0) {
+    if (OPENSSL_memcmp(buf, test->out, test->out_len) != 0) {
       fprintf(stderr,
               "%zu: Resulting key material does not match test vector\n", i);
       return 1;