diff --git a/lisp/progmodes/xref.el b/lisp/progmodes/xref.el
index feed0fb..6cc8dc1 100644
--- a/lisp/progmodes/xref.el
+++ b/lisp/progmodes/xref.el
@@ -992,6 +992,7 @@ xref--collect-matches
               (line-beg (line-beginning-position))
               matches)
           (syntax-propertize line-end)
+          (font-lock-ensure line-beg line-end)
           ;; FIXME: This results in several lines with the same
           ;; summary. Solve with composite pattern?
           (while (re-search-forward regexp line-end t)