diff --git a/metis_l2_prep_uv.pro b/metis_l2_prep_uv.pro
index 8be8bfa122b051b003a13c0d68d82f4907a168fd..58b30a2e4f9603fe7711bbbc57f94d9e8324f051 100644
--- a/metis_l2_prep_uv.pro
+++ b/metis_l2_prep_uv.pro
@@ -166,6 +166,7 @@ pro metis_l2_prep_uv
 
 	; update the comment and history keywords
 
+	fxaddpar, primary_header, 'COMMENT', 'WARNING: UV radiometric calibration is still preliminary.'
 	fxaddpar, primary_header, 'COMMENT', 'Uncertainty matrix in the FITS extension is preliminary.'
 
 	for k = 0, n_elements(history) - 1 do $