diff --git a/library/psa_crypto_mac.c b/library/psa_crypto_mac.c
index 19671ec..cf20a9b 100644
--- a/library/psa_crypto_mac.c
+++ b/library/psa_crypto_mac.c
@@ -127,7 +127,7 @@
     uint8_t *mac,
     size_t mac_size )
 {
-    uint8_t tmp[MBEDTLS_MD_MAX_SIZE];
+    uint8_t tmp[PSA_HASH_MAX_SIZE];
     psa_algorithm_t hash_alg = hmac->alg;
     size_t hash_size = 0;
     size_t block_size = PSA_HASH_BLOCK_LENGTH( hash_alg );