(fill-context-prefix): Don't crash if RESULT is nil when AT-SECOND is t.

1 files changed, 5 insertions, 4 deletions

diff --git a/lisp/textmodes/fill.el b/lisp/textmodes/fill.el
index 552bd4fb68c..c3628be99f8 100644
--- a/lisp/textmodes/fill.el
+++ b/lisp/textmodes/fill.el
@@ -200,10 +200,11 @@ act as a paragraph-separator."
         (if at-second
             ;; If we get a fill prefix from the second line,
             ;; make sure it's on the first line too.
-            (save-excursion
-              (forward-line -1)
-              (if (looking-at (regexp-quote result))
-                  result))
+            (and result
+                 (save-excursion
+                   (forward-line -1)
+                   (if (looking-at (regexp-quote result))
+                       result)))
           ;; If we get a fill prefix from a one-line paragraph,
           ;; maybe change it to whitespace,
           ;; and check that it isn't a paragraph starter.