diff --git a/src/procmime.c b/src/procmime.c
index 252ec29..89afd0a 100644
--- a/src/procmime.c
+++ b/src/procmime.c
@@ -1704,7 +1704,7 @@ static void parse_parameters(const gchar *parameters, GHashTable *table)
 			    (g_slist_find_custom(concatlist, down_attr, g_strcmp0) == NULL))
 				concatlist = g_slist_prepend(concatlist, g_strdup(tmpattr));
 
-			if (convert && (g_slist_find_custom(convlist, down_attr, g_strcmp0) == NULL))
+			if (convert && (g_slist_find_custom(convlist, tmpattr, g_strcmp0) == NULL))
 				convlist = g_slist_prepend(convlist, g_strdup(tmpattr));
 
 			g_free(tmpattr);