diff --git a/tests/suites/test_suite_aes.function b/tests/suites/test_suite_aes.function
index e998795..d781d2e 100644
--- a/tests/suites/test_suite_aes.function
+++ b/tests/suites/test_suite_aes.function
@@ -169,10 +169,11 @@
     key_len = unhexify( key_str, hex_key_string );
     unhexify( iv_str, hex_iv_string );
     data_len = unhexify( src_str, hex_src_string );
+    TEST_ASSERT( data_len == data_unit_len / 8 );
 
     mbedtls_aes_xts_setkey_enc( &ctx, key_str, key_len * 8 );
 
-    TEST_ASSERT( mbedtls_aes_crypt_xts( &ctx, MBEDTLS_AES_ENCRYPT, data_unit_len, iv_str, src_str, output ) == xts_result );
+    TEST_ASSERT( mbedtls_aes_crypt_xts( &ctx, MBEDTLS_AES_ENCRYPT, data_len, iv_str, src_str, output ) == xts_result );
     if( xts_result == 0 )
     {
         hexify( dst_str, output, data_len );
@@ -203,10 +204,11 @@
     key_len = unhexify( key_str, hex_key_string );
     unhexify( iv_str, hex_iv_string );
     data_len = unhexify( src_str, hex_src_string );
+    TEST_ASSERT( data_len == data_unit_len / 8 );
 
     mbedtls_aes_xts_setkey_dec( &ctx, key_str, key_len * 8 );
 
-    TEST_ASSERT( mbedtls_aes_crypt_xts( &ctx, MBEDTLS_AES_DECRYPT, data_unit_len, iv_str, src_str, output ) == xts_result );
+    TEST_ASSERT( mbedtls_aes_crypt_xts( &ctx, MBEDTLS_AES_DECRYPT, data_len, iv_str, src_str, output ) == xts_result );
     if( xts_result == 0 )
     {
         hexify( dst_str, output, data_len );