diff --git a/src/libsodium/crypto_onetimeauth/crypto_onetimeauth.c b/src/libsodium/crypto_onetimeauth/crypto_onetimeauth.c
index 2af0fdac..1e90d620 100644
--- a/src/libsodium/crypto_onetimeauth/crypto_onetimeauth.c
+++ b/src/libsodium/crypto_onetimeauth/crypto_onetimeauth.c
@@ -1,6 +1,12 @@
 
 #include "crypto_onetimeauth.h"
 
+size_t
+crypto_onetimeauth_statebytes(void)
+{
+    return sizeof(crypto_onetimeauth_state);
+}
+
 size_t
 crypto_onetimeauth_bytes(void)
 {
@@ -13,12 +19,6 @@ crypto_onetimeauth_keybytes(void)
     return crypto_onetimeauth_KEYBYTES;
 }
 
-const char *
-crypto_onetimeauth_primitive(void)
-{
-    return crypto_onetimeauth_PRIMITIVE;
-}
-
 int
 crypto_onetimeauth(unsigned char *out, const unsigned char *in,
                    unsigned long long inlen, const unsigned char *k)
@@ -57,3 +57,9 @@ crypto_onetimeauth_final(crypto_onetimeauth_state *state,
     return crypto_onetimeauth_poly1305_final
         ((crypto_onetimeauth_poly1305_state *) state, out);
 }
+
+const char *
+crypto_onetimeauth_primitive(void)
+{
+    return crypto_onetimeauth_PRIMITIVE;
+}
diff --git a/src/libsodium/include/sodium/crypto_onetimeauth.h b/src/libsodium/include/sodium/crypto_onetimeauth.h
index 02d41a9e..318f672d 100644
--- a/src/libsodium/include/sodium/crypto_onetimeauth.h
+++ b/src/libsodium/include/sodium/crypto_onetimeauth.h
@@ -14,6 +14,8 @@ extern "C" {
 #endif
 
 typedef crypto_onetimeauth_poly1305_state crypto_onetimeauth_state;
+SODIUM_EXPORT
+size_t  crypto_onetimeauth_statebytes(void);
 
 #define crypto_onetimeauth_BYTES crypto_onetimeauth_poly1305_BYTES
 SODIUM_EXPORT
diff --git a/test/default/onetimeauth.c b/test/default/onetimeauth.c
index 9a8b4f5d..d92a8b65 100644
--- a/test/default/onetimeauth.c
+++ b/test/default/onetimeauth.c
@@ -27,6 +27,7 @@ int main(void)
     crypto_onetimeauth_state st;
     int i;
 
+    assert(crypto_onetimeauth_statebytes() == sizeof st);
     crypto_onetimeauth(a, c, 131, rs);
     for (i = 0; i < 16; ++i) {
         printf(",0x%02x", (unsigned int)a[i]);