diff --git a/Maintenance/test_handling/to_zipped_format b/Maintenance/test_handling/to_zipped_format
index fdf62712b02..9131d100065 100755
--- a/Maintenance/test_handling/to_zipped_format
+++ b/Maintenance/test_handling/to_zipped_format
@@ -117,7 +117,7 @@ sub reformat_results($)
 #	if (/BOOST_BIMAP_VERSION = '([^']+)'/) {
 #	    $BOOST="$BOOST+bimap";
 #	}
-	if (/USING +CXXFLAGS = '([^']*)'/) {
+	if (/USING +CXXFLAGS = '([^']*)'/ && !$CXXFLAGS) {
 	    $CXXFLAGS="$CXXFLAGS $1";
 	}
 	if (/USING +LDFLAGS = '([^']*)'/) {