--- grep-2.5.1a/src/search.c.w	2006-02-20 14:27:27.000000000 +0000
+++ grep-2.5.1a/src/search.c	2006-02-20 14:32:07.000000000 +0000
@@ -507,10 +507,114 @@
 	      if (match_words)
 		while (start >= 0)
 		  {
-		    if ((start == 0 || !WCHAR ((unsigned char) beg[start - 1]))
-			&& (len == end - beg - 1
-			    || !WCHAR ((unsigned char) beg[start + len])))
-		      goto success_in_beg_and_end;
+		    int lword_match = 0;
+		    if (start == 0)
+		      lword_match = 1;
+		    else
+		      {
+			assert (start > 0);
+#ifdef MBS_SUPPORT
+			if (mb_cur_max > 1)
+			  {
+			    const char *s;
+			    size_t mr;
+			    wchar_t pwc;
+
+			    /* Locate the start of the multibyte character
+			       before the match position (== beg + start). */
+			    if (using_utf8)
+			      {
+				/* UTF-8 is a special case: scan backwards
+				   until we find a 7-bit character or a
+				   lead byte. */
+				s = beg + start - 1;
+				while (s > buf
+				       && (unsigned char) *s >= 0x80
+				       && (unsigned char) *s <= 0xbf)
+				  --s;
+			      }
+			    else
+			      {
+				/* Scan forwards to find the start of the
+				   last complete character before the
+				   match position.  */
+				size_t bytes_left = start - 1;
+				s = beg;
+				while (bytes_left > 0)
+				  {
+				    mr = mbrlen (s, bytes_left, &mbs);
+				    if (mr == (size_t) -1 || mr == 0)
+				      {
+					memset (&mbs, '\0', sizeof (mbs));
+					s++;
+					bytes_left--;
+					continue;
+				      }
+				    if (mr == (size_t) -2)
+				      {
+					memset (&mbs, '\0', sizeof (mbs));
+					break;
+				      }
+				    s += mr;
+				    bytes_left -= mr;
+				  }
+			      }
+			    mr = mbrtowc (&pwc, s, beg + start - s, &mbs);
+			    if (mr == (size_t) -2 || mr == (size_t) -1 ||
+				mr == 0)
+			      {
+				memset (&mbs, '\0', sizeof (mbstate_t));
+				lword_match = 1;
+			      }
+			    else if (!(iswalnum (pwc) || pwc == L'_')
+				     && mr == beg + start - s)
+			      lword_match = 1;
+			  }
+			else
+#endif /* MBS_SUPPORT */
+			if (!WCHAR ((unsigned char) beg[start - 1]))
+			  lword_match = 1;
+		      }
+
+		    if (lword_match)
+		      {
+			int rword_match = 0;
+			if (start + len == end - beg - 1)
+			  rword_match = 1;
+			else
+			  {
+#ifdef MBS_SUPPORT
+			    if (mb_cur_max > 1)
+			      {
+				wchar_t nwc;
+				int mr;
+
+				mr = mbtowc (&nwc, beg + start + len,
+					     end - beg - start - len - 1);
+				if (mr <= 0)
+				  {
+				    memset (&mbs, '\0', sizeof (mbstate_t));
+				    rword_match = 1;
+				  }
+				else if (!iswalnum (nwc) && nwc != L'_')
+				  rword_match = 1;
+			      }
+			    else
+#endif /* MBS_SUPPORT */
+			    if (!WCHAR ((unsigned char) beg[start + len]))
+			      rword_match = 1;
+			  }
+
+			if (rword_match)
+			  {
+			    if (!exact)
+			      /* Returns the whole line. */
+			      goto success_in_beg_and_end;
+			    else
+			      /* Returns just this word match. */
+			      goto success_in_start_and_len;
+			  }
+		      }
 		    if (len > 0)
 		      {
 			/* Try a shorter length anchored at the same place. */