--- flyspell.el.orig	2005-12-22 12:23:55.000000000 +0100
+++ flyspell.el	2005-12-22 12:49:28.000000000 +0100
@@ -1325,6 +1325,9 @@
 		       (* 100 (/ (float (point)) (point-max)))
 		       word))
 	  (with-current-buffer flyspell-large-region-buffer
+	    ;; Make sure search starts from last validated match (or from
+	    ;; beginning of region if the first time). This intends to avoid
+	    ;; erroneous forward jumps that might cause fatal forward unsyncs.
 	    (goto-char flyspell-large-region-beg)
 	    (let ((keep t))
 	      ;; Iterate on string search until string is found as word,
@@ -1334,15 +1337,21 @@
 				    flyspell-large-region-end t)
 		    (save-excursion
 		      (goto-char (- (point) 1))
-		      (let* ((flyword-prev-l (flyspell-get-word nil))
+		      (let* ((match-point (+ (point) 1))
+			     (flyword-prev-l (flyspell-get-word nil))
 			     (flyword-prev (car flyword-prev-l))
-			     (size-match (= (length flyword-prev) (length word))))
+			     (flyword-length (length flyword-prev))
+			     (misspell-length (length word)))
 			(when (or
-			       ;; size matches, we are done
-			       size-match
+			       ;; Size matches, we are done
+			       (= flyword-length misspell-length)
 			       ;; Matches as part of a boundary-char separated word
 			       (member word
 				       (split-string flyword-prev ispell-otherchars))
+			       ;; Misspelling has higher length than what flyspell
+			       ;; considers the word. Caused by boundary-chars mismatch.
+			       ;; Validating seems safe.
+			       (< flyword-length misspell-length)
 			       ;; ispell treats beginning of some TeX
 			       ;; commands as nroff control sequences
 			       ;; and strips them in the list of
@@ -1360,8 +1369,9 @@
 					nil))))
 			  (setq keep nil)
 			  (flyspell-word)
-			  ;; Next search will begin from end of last match
-			  )))
+			  ;; Search for next misspelled word will begin from
+			  ;; end of last validated match.
+			  (setq flyspell-large-region-beg match-point))))
 		  ;; Record if misspelling is not found and try new one
 		  (add-to-list 'words-not-found
 			       (concat " -> " word " - "