diff --git a/src/libsodium/crypto_shorthash/siphash24/shorthash_siphash24_api.c b/src/libsodium/crypto_shorthash/siphash24/shorthash_siphash24_api.c
index dd60202c..52f96b55 100644
--- a/src/libsodium/crypto_shorthash/siphash24/shorthash_siphash24_api.c
+++ b/src/libsodium/crypto_shorthash/siphash24/shorthash_siphash24_api.c
@@ -5,6 +5,11 @@ crypto_shorthash_siphash24_bytes(void) {
     return crypto_shorthash_siphash24_BYTES;
 }
 
+size_t
+crypto_shorthash_siphash24_keybytes(void) {
+    return crypto_shorthash_siphash24_KEYBYTES;
+}
+
 const char *
 crypto_shorthash_siphash24_primitive(void) {
     return "siphash24";
diff --git a/src/libsodium/include/sodium/crypto_shorthash_siphash24.h b/src/libsodium/include/sodium/crypto_shorthash_siphash24.h
index c1ed2cd5..94513ee6 100644
--- a/src/libsodium/include/sodium/crypto_shorthash_siphash24.h
+++ b/src/libsodium/include/sodium/crypto_shorthash_siphash24.h
@@ -17,6 +17,9 @@ extern "C" {
 SODIUM_EXPORT
 size_t crypto_shorthash_siphash24_bytes(void);
 
+SODIUM_EXPORT
+size_t crypto_shorthash_siphash24_keybytes(void);
+
 SODIUM_EXPORT
 const char * crypto_shorthash_siphash24_primitive(void);