1 files changed, 26 insertions, 7 deletions

diff --git a/lisp/textmodes/fill.el b/lisp/textmodes/fill.el
index 57d7804657f..b5017b22a9d 100644
--- a/lisp/textmodes/fill.el
+++ b/lisp/textmodes/fill.el
@@ -165,12 +165,24 @@ From program, pass args FROM, TO and JUSTIFY-FLAG."
                         (eq (char-after (- (point) 2)) ?\.))
               (forward-char -2)
               (skip-chars-backward "^ \n" linebeg))
-            (if (if (zerop prefixcol) (bolp) (>= prefixcol (current-column)))
+            (if (if (zerop prefixcol)
+                    (save-excursion
+                      (skip-chars-backward " " linebeg)
+                      (bolp))
+                  (>= prefixcol (current-column)))
                 ;; Keep at least one word even if fill prefix exceeds margin.
                 ;; This handles all but the first line of the paragraph.
-                (progn
-                  (skip-chars-forward " ")
-                  (skip-chars-forward "^ \n"))
+                ;; Meanwhile, don't stop at a period followed by one space.
+                (let ((first t))
+                  (move-to-column prefixcol)
+                  (while (and (not (eobp))
+                              (or first
+                                  (and (not (bobp))
+                                       (save-excursion (forward-char -1)
+                                                       (looking-at "\\. ")))))
+                    (skip-chars-forward " ")
+                    (skip-chars-forward "^ \n")
+                    (setq first nil)))
               ;; Normally, move back over the single space between the words.
               (forward-char -1))
             (if (and fill-prefix (zerop prefixcol)
@@ -179,9 +191,16 @@ From program, pass args FROM, TO and JUSTIFY-FLAG."
                               (substring fill-prefix 0 (- (point) (point-min)))))
                 ;; Keep at least one word even if fill prefix exceeds margin.
                 ;; This handles the first line of the paragraph.
-                (progn
-                  (skip-chars-forward " ")
-                  (skip-chars-forward "^ \n"))))
+                ;; Don't stop at a period followed by just one space.
+                (let ((first t))
+                  (while (and (not (eobp))
+                              (or first
+                                  (and (not (bobp))
+                                       (save-excursion (forward-char -1)
+                                                       (looking-at "\\. ")))))
+                    (skip-chars-forward " ")
+                    (skip-chars-forward "^ \n")
+                    (setq first nil)))))
           ;; Replace all whitespace here with one newline.
           ;; Insert before deleting, so we don't forget which side of
           ;; the whitespace point or markers used to be on.