diff --git a/crypto/cryptlib.c b/crypto/cryptlib.c
index 9473799a4..d31734068 100644
--- a/crypto/cryptlib.c
+++ b/crypto/cryptlib.c
@@ -465,7 +465,9 @@ void OpenSSLDie(const char *file, int line, const char *assertion)
 #endif
 }
 
-int CRYPTO_memcmp(const volatile void *in_a, const volatile void *in_b, size_t len)
+int CRYPTO_memcmp(const volatile void * volatile in_a,
+                  const volatile void * volatile in_b,
+                  size_t len)
 {
     size_t i;
     const volatile unsigned char *a = in_a;
diff --git a/include/openssl/crypto.h b/include/openssl/crypto.h
index 024f2c9b7..1251aa13d 100644
--- a/include/openssl/crypto.h
+++ b/include/openssl/crypto.h
@@ -542,7 +542,9 @@ int OPENSSL_gmtime_diff(int *pday, int *psec,
  * into a defined order as the return value when a != b is undefined, other
  * than to be non-zero.
  */
-int CRYPTO_memcmp(const volatile void *a, const volatile void *b, size_t len);
+int CRYPTO_memcmp(const volatile void * volatile in_a,
+                  const volatile void * volatile in_b,
+                  size_t len);
 
 /* BEGIN ERROR CODES */
 /*