1 files changed, 1 insertions, 0 deletions

diff --git a/lisp/textmodes/fill.el b/lisp/textmodes/fill.el
index a4b515c0b65..534e5e9d754 100644
--- a/lisp/textmodes/fill.el
+++ b/lisp/textmodes/fill.el
@@ -1087,6 +1087,7 @@ Also, if CITATION-REGEXP is non-nil,  don't fill header lines."
                     (fill-individual-paragraphs-citation two-lines-prefix
                                                          citation-regexp)
                   just-one-line-prefix))
+          (or two-lines-citation-part (setq two-lines-citation-part ""))
           (setq adjusted-two-lines-citation-part
                 (substring two-lines-citation-part 0
                            (string-match "[ \t]*\\'"