diff --git a/src/libsodium/crypto_generichash/blake2/generichash_blake2_api.c b/src/libsodium/crypto_generichash/blake2/generichash_blake2_api.c
index b775921e..14f16e42 100644
--- a/src/libsodium/crypto_generichash/blake2/generichash_blake2_api.c
+++ b/src/libsodium/crypto_generichash/blake2/generichash_blake2_api.c
@@ -39,3 +39,10 @@ size_t
 crypto_generichash_blake2b_personalbytes(void) {
     return crypto_generichash_blake2b_PERSONALBYTES;
 }
+
+size_t
+crypto_generichash_blake2b_statebytes(void)
+{
+    return (sizeof(crypto_generichash_blake2b_state) + (size_t) 63U)
+        & ~(size_t) 63U;
+}
diff --git a/src/libsodium/include/sodium/crypto_generichash_blake2b.h b/src/libsodium/include/sodium/crypto_generichash_blake2b.h
index 1708813e..3998e1bd 100644
--- a/src/libsodium/include/sodium/crypto_generichash_blake2b.h
+++ b/src/libsodium/include/sodium/crypto_generichash_blake2b.h
@@ -67,6 +67,9 @@ size_t crypto_generichash_blake2b_saltbytes(void);
 SODIUM_EXPORT
 size_t crypto_generichash_blake2b_personalbytes(void);
 
+SODIUM_EXPORT
+size_t crypto_generichash_blake2b_statebytes(void);
+
 SODIUM_EXPORT
 int crypto_generichash_blake2b(unsigned char *out, size_t outlen,
                                const unsigned char *in,
diff --git a/test/default/generichash3.c b/test/default/generichash3.c
index e430b725..fa0045e2 100644
--- a/test/default/generichash3.c
+++ b/test/default/generichash3.c
@@ -20,6 +20,7 @@ main(void)
     size_t        i;
     size_t        j;
 
+    assert(crypto_generichash_blake2b_statebytes() >= sizeof st);
     for (h = 0; h < crypto_generichash_blake2b_KEYBYTES_MAX; ++h) {
         k[h] = (unsigned char) h;
     }