diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index aaaa8a5..beb5f55 100755
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -1669,7 +1669,11 @@
 
         mbedtls_ccm_free( &ccm );
     }
-
+    else
+    {
+        return( PSA_ERROR_INVALID_ARGUMENT );
+    }
+    
     *plaintext_length = ciphertext_length;
     return( PSA_SUCCESS );
 }