diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 217e904..0a9abda 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -3526,6 +3526,9 @@
 
     *ciphertext_length = 0;
 
+    if( !PSA_ALG_IS_AEAD( alg ) || PSA_ALG_IS_WILDCARD( alg ) )
+        return( PSA_ERROR_NOT_SUPPORTED );
+
     status = psa_get_and_lock_key_slot_with_policy(
                  key, &slot, PSA_KEY_USAGE_ENCRYPT, alg );
     if( status != PSA_SUCCESS )
@@ -3568,6 +3571,9 @@
 
     *plaintext_length = 0;
 
+    if( !PSA_ALG_IS_AEAD( alg ) || PSA_ALG_IS_WILDCARD( alg ) )
+        return( PSA_ERROR_NOT_SUPPORTED );
+
     status = psa_get_and_lock_key_slot_with_policy(
                  key, &slot, PSA_KEY_USAGE_DECRYPT, alg );
     if( status != PSA_SUCCESS )