diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index baac97c..35bd42e 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -5541,7 +5541,7 @@
 cleanup:
     /* Zeroise buffers to clear sensitive data from memory. */
     mbedtls_platform_zeroize(U_accumulator, PSA_MAC_MAX_SIZE);
-    mbedtls_platform_zeroize(U_i, PSA_MAC_MAX_SIZE); 
+    mbedtls_platform_zeroize(U_i, PSA_MAC_MAX_SIZE);
     return status;
 }
 
@@ -5562,6 +5562,8 @@
         prf_alg = PSA_ALG_HMAC(PSA_ALG_PBKDF2_HMAC_GET_HASH(kdf_alg));
         prf_output_length = PSA_HASH_LENGTH(prf_alg);
         psa_set_key_type(&attributes, PSA_KEY_TYPE_HMAC);
+    } else {
+        return PSA_ERROR_INVALID_ARGUMENT;
     }
 
     switch (pbkdf2->state) {