diff --git a/src/libsodium/crypto_kdf/hkdf/kdf_hkdf_sha512.c b/src/libsodium/crypto_kdf/hkdf/kdf_hkdf_sha512.c
index 51d91619..cb3735fe 100644
--- a/src/libsodium/crypto_kdf/hkdf/kdf_hkdf_sha512.c
+++ b/src/libsodium/crypto_kdf/hkdf/kdf_hkdf_sha512.c
@@ -116,3 +116,8 @@ crypto_kdf_hkdf_sha512_bytes_max(void)
 {
     return crypto_kdf_hkdf_sha512_BYTES_MAX;
 }
+
+size_t crypto_kdf_hkdf_sha512_statebytes(void)
+{
+    return sizeof(crypto_kdf_hkdf_sha512_state);
+}
diff --git a/test/default/kdf_hkdf.c b/test/default/kdf_hkdf.c
index 8fb07fe5..c3362770 100644
--- a/test/default/kdf_hkdf.c
+++ b/test/default/kdf_hkdf.c
@@ -81,10 +81,12 @@ tv_kdf_hkdf(void)
     assert(crypto_kdf_hkdf_sha512_bytes_min() == crypto_kdf_hkdf_sha512_BYTES_MIN);
     assert(crypto_kdf_hkdf_sha512_bytes_max() == crypto_kdf_hkdf_sha512_BYTES_MAX);
     assert(crypto_kdf_hkdf_sha512_keybytes() == crypto_kdf_hkdf_sha512_KEYBYTES);
+    assert(crypto_kdf_hkdf_sha512_statebytes() >= sizeof (crypto_kdf_hkdf_sha512_state));
 
     assert(crypto_kdf_hkdf_sha256_bytes_min() == crypto_kdf_hkdf_sha256_BYTES_MIN);
     assert(crypto_kdf_hkdf_sha256_bytes_max() == crypto_kdf_hkdf_sha256_BYTES_MAX);
     assert(crypto_kdf_hkdf_sha256_keybytes() == crypto_kdf_hkdf_sha256_KEYBYTES);
+    assert(crypto_kdf_hkdf_sha256_statebytes() >= sizeof (crypto_kdf_hkdf_sha256_state));
 
     assert(crypto_kdf_hkdf_sha256_KEYBYTES < crypto_kdf_hkdf_sha512_KEYBYTES);