diff --git a/src/libsodium/crypto_hash/sha256/cp/hash_sha256.c b/src/libsodium/crypto_hash/sha256/cp/hash_sha256.c
index 0eb330e2..82cf94bd 100644
--- a/src/libsodium/crypto_hash/sha256/cp/hash_sha256.c
+++ b/src/libsodium/crypto_hash/sha256/cp/hash_sha256.c
@@ -232,8 +232,9 @@ crypto_hash_sha256_update(crypto_hash_sha256_state *state,
         in += 64;
         inlen -= 64;
     }
-    memcpy(state->buf, in, inlen); /* inlen < 64 */
-
+    if (inlen > 0) {
+        memcpy(state->buf, in, inlen); /* inlen < 64 */
+    }
     return 0;
 }
 
diff --git a/src/libsodium/crypto_hash/sha512/cp/hash_sha512.c b/src/libsodium/crypto_hash/sha512/cp/hash_sha512.c
index 4e6b515c..55af8a0f 100644
--- a/src/libsodium/crypto_hash/sha512/cp/hash_sha512.c
+++ b/src/libsodium/crypto_hash/sha512/cp/hash_sha512.c
@@ -262,8 +262,9 @@ crypto_hash_sha512_update(crypto_hash_sha512_state *state,
         src += 128;
         inlen -= 128;
     }
-    memcpy(state->buf, src, inlen); /* inlen < 128 */
-
+    if (inlen > 0) {
+        memcpy(state->buf, src, inlen); /* inlen < 128 */
+    }
     return 0;
 }