diff --git a/src/globals.h b/src/globals.h
index d6e879a..ffb2050 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -801,7 +801,7 @@
 EXTERN int (*mb_char2bytes) __ARGS((int c, char_u *buf)) INIT(= latin_char2bytes);
 EXTERN int (*mb_ptr2cells) __ARGS((char_u *p)) INIT(= latin_ptr2cells);
 EXTERN int (*mb_char2cells) __ARGS((int c)) INIT(= latin_char2cells);
-EXTERN int (*mb_off2cells) __ARGS((unsigned off)) INIT(= latin_off2cells);
+EXTERN int (*mb_off2cells) __ARGS((unsigned off, unsigned max_off)) INIT(= latin_off2cells);
 EXTERN int (*mb_ptr2char) __ARGS((char_u *p)) INIT(= latin_ptr2char);
 EXTERN int (*mb_head_off) __ARGS((char_u *base, char_u *p)) INIT(= latin_head_off);
 
diff --git a/src/gui.c b/src/gui.c
index 4516b69..dcd81df 100644
--- a/src/gui.c
+++ b/src/gui.c
@@ -1080,7 +1080,8 @@
 		cur_width = gui.char_width;
 	    }
 #ifdef FEAT_MBYTE
-	    if (has_mbyte && (*mb_off2cells)(LineOffset[gui.row] + gui.col) > 1)
+	    if (has_mbyte && (*mb_off2cells)(LineOffset[gui.row] + gui.col,
+				    LineOffset[gui.row] + screen_Columns) > 1)
 	    {
 		/* Double wide character. */
 		if (shape_table[idx].shape != SHAPE_VER)
@@ -1159,7 +1160,7 @@
 #endif
 
 # if defined(FEAT_GUI_TABLINE) && (defined(FEAT_GUI_MSWIN) \
- 	|| defined(FEAT_GUI_MOTIF) || defined(FEAT_GUI_MAC))
+	|| defined(FEAT_GUI_MOTIF) || defined(FEAT_GUI_MAC))
     if (gui_has_tabline())
 	text_area_y += gui.tabline_height;
 #endif
diff --git a/src/mbyte.c b/src/mbyte.c
index bf6fbb3..b2303fd 100644
--- a/src/mbyte.c
+++ b/src/mbyte.c
@@ -1310,20 +1310,26 @@
 /*
  * mb_off2cells() function pointer.
  * Return number of display cells for char at ScreenLines[off].
- * Caller must make sure "off" and "off + 1" are valid!
+ * We make sure that the offset used is less than "max_off".
  */
 /*ARGSUSED*/
     int
-latin_off2cells(off)
+latin_off2cells(off, max_off)
     unsigned	off;
+    unsigned	max_off;
 {
     return 1;
 }
 
     int
-dbcs_off2cells(off)
+dbcs_off2cells(off, max_off)
     unsigned	off;
+    unsigned	max_off;
 {
+    /* never check beyond end of the line */
+    if (off >= max_off)
+	return 1;
+
     /* Number of cells is equal to number of bytes, except for euc-jp when
      * the first byte is 0x8e. */
     if (enc_dbcs == DBCS_JPNU && ScreenLines[off] == 0x8e)
@@ -1332,10 +1338,11 @@
 }
 
     int
-utf_off2cells(off)
+utf_off2cells(off, max_off)
     unsigned	off;
+    unsigned	max_off;
 {
-    return ScreenLines[off + 1] == 0 ? 2 : 1;
+    return (off + 1 < max_off && ScreenLines[off + 1] == 0) ? 2 : 1;
 }
 
 /*
@@ -2899,12 +2906,8 @@
     if (composing_hangul)
 	return TRUE;
 #endif
-    if (enc_dbcs != 0)
-	return dbcs_off2cells(LineOffset[row] + col) > 1;
-    if (enc_utf8)
-	return (col + 1 < Columns
-		&& ScreenLines[LineOffset[row] + col + 1] == 0);
-    return FALSE;
+    return (*mb_off2cells)(LineOffset[row] + col,
+					LineOffset[row] + screen_Columns) > 1;
 }
 
 # if defined(FEAT_CLIPBOARD) || defined(FEAT_GUI) || defined(FEAT_RIGHTLEFT) \
diff --git a/src/proto/mbyte.pro b/src/proto/mbyte.pro
index 16a36c8..ef11dc7 100644
--- a/src/proto/mbyte.pro
+++ b/src/proto/mbyte.pro
@@ -12,9 +12,9 @@
 int utf_ptr2cells __ARGS((char_u *p));
 int dbcs_ptr2cells __ARGS((char_u *p));
 int latin_char2cells __ARGS((int c));
-int latin_off2cells __ARGS((unsigned off));
-int dbcs_off2cells __ARGS((unsigned off));
-int utf_off2cells __ARGS((unsigned off));
+int latin_off2cells __ARGS((unsigned off, unsigned max_off));
+int dbcs_off2cells __ARGS((unsigned off, unsigned max_off));
+int utf_off2cells __ARGS((unsigned off, unsigned max_off));
 int latin_ptr2char __ARGS((char_u *p));
 int utf_ptr2char __ARGS((char_u *p));
 int mb_ptr2char_adv __ARGS((char_u **pp));
diff --git a/src/screen.c b/src/screen.c
index 009968b..770187b 100644
--- a/src/screen.c
+++ b/src/screen.c
@@ -1024,7 +1024,7 @@
 	    type = VALID;
     }
 
-    /* Trick: we want to avoid clearning the screen twice.  screenclear() will
+    /* Trick: we want to avoid clearing the screen twice.  screenclear() will
      * set "screen_cleared" to TRUE.  The special value MAYBE (which is still
      * non-zero and thus not FALSE) will indicate that screenclear() was not
      * called. */
@@ -4632,7 +4632,7 @@
 
 	/*
 	 * At end of screen line and there is more to come: Display the line
-	 * so far.  If there is no more to display it is catched above.
+	 * so far.  If there is no more to display it is caught above.
 	 */
 	if ((
 #ifdef FEAT_RIGHTLEFT
@@ -4709,9 +4709,13 @@
 #endif
 #ifdef FEAT_MBYTE
 			 && !(has_mbyte
-			     && ((*mb_off2cells)(LineOffset[screen_row]) == 2
+			     && ((*mb_off2cells)(LineOffset[screen_row],
+				     LineOffset[screen_row] + screen_Columns)
+									  == 2
 				 || (*mb_off2cells)(LineOffset[screen_row - 1]
-							+ (int)Columns - 2) == 2))
+							+ (int)Columns - 2,
+				     LineOffset[screen_row] + screen_Columns)
+									== 2))
 #endif
 		   )
 		{
@@ -4871,6 +4875,10 @@
 {
     unsigned	    off_from;
     unsigned	    off_to;
+#ifdef FEAT_MBYTE
+    unsigned	    max_off_from;
+    unsigned	    max_off_to;
+#endif
     int		    col = 0;
 #if defined(FEAT_GUI) || defined(UNIX) || defined(FEAT_VERTSPLIT)
     int		    hl;
@@ -4897,6 +4905,10 @@
 
     off_from = (unsigned)(current_ScreenLine - ScreenLines);
     off_to = LineOffset[row] + coloff;
+#ifdef FEAT_MBYTE
+    max_off_from = off_from + screen_Columns;
+    max_off_to = LineOffset[row] + screen_Columns;
+#endif
 
 #ifdef FEAT_RIGHTLEFT
     if (rlflag)
@@ -4931,7 +4943,7 @@
     {
 #ifdef FEAT_MBYTE
 	if (has_mbyte && (col + 1 < endcol))
-	    char_cells = (*mb_off2cells)(off_from);
+	    char_cells = (*mb_off2cells)(off_from, max_off_from);
 	else
 	    char_cells = 1;
 #endif
@@ -5008,7 +5020,7 @@
 		 * ScreenLinesUC[] is sufficient. */
 		if (char_cells == 1
 			&& col + 1 < endcol
-			&& (*mb_off2cells)(off_to) > 1)
+			&& (*mb_off2cells)(off_to, max_off_to) > 1)
 		{
 		    /* Writing a single-cell character over a double-cell
 		     * character: need to redraw the next cell. */
@@ -5017,8 +5029,8 @@
 		}
 		else if (char_cells == 2
 			&& col + 2 < endcol
-			&& (*mb_off2cells)(off_to) == 1
-			&& (*mb_off2cells)(off_to + 1) > 1)
+			&& (*mb_off2cells)(off_to, max_off_to) == 1
+			&& (*mb_off2cells)(off_to + 1, max_off_to) > 1)
 		{
 		    /* Writing the second half of a double-cell character over
 		     * a double-cell character: need to redraw the second
@@ -5037,10 +5049,10 @@
 	     * char over the left halve of an existing one. */
 	    if (has_mbyte && col + char_cells == endcol
 		    && ((char_cells == 1
-			    && (*mb_off2cells)(off_to) > 1)
+			    && (*mb_off2cells)(off_to, max_off_to) > 1)
 			|| (char_cells == 2
-			    && (*mb_off2cells)(off_to) == 1
-			    && (*mb_off2cells)(off_to + 1) > 1)))
+			    && (*mb_off2cells)(off_to, max_off_to) == 1
+			    && (*mb_off2cells)(off_to + 1, max_off_to) > 1)))
 		clear_next = TRUE;
 #endif
 
@@ -5180,10 +5192,11 @@
 			/* find previous character by counting from first
 			 * column and get its width. */
 			unsigned off = LineOffset[row];
+			unsigned max_off = LineOffset[row] + screen_Columns;
 
 			while (off < off_to)
 			{
-			    prev_cells = (*mb_off2cells)(off);
+			    prev_cells = (*mb_off2cells)(off, max_off);
 			    off += prev_cells;
 			}
 		    }
@@ -5369,7 +5382,7 @@
 static int skip_status_match_char __ARGS((expand_T *xp, char_u *s));
 
 /*
- * Get the lenght of an item as it will be shown in the status line.
+ * Get the length of an item as it will be shown in the status line.
  */
     static int
 status_match_len(xp, s)
@@ -5435,7 +5448,7 @@
     int		row;
     char_u	*buf;
     int		len;
-    int		clen;		/* lenght in screen cells */
+    int		clen;		/* length in screen cells */
     int		fillchar;
     int		attr;
     int		i;
@@ -6187,6 +6200,7 @@
     char_u	*ptr = text;
     int		c;
 #ifdef FEAT_MBYTE
+    unsigned	max_off;
     int		mbyte_blen = 1;
     int		mbyte_cells = 1;
     int		u8c = 0;
@@ -6203,6 +6217,9 @@
 	return;
 
     off = LineOffset[row] + col;
+#ifdef FEAT_MBYTE
+    max_off = LineOffset[row] + screen_Columns;
+#endif
     while (col < screen_Columns
 	    && (len < 0 || (int)(ptr - text) < len)
 	    && *ptr != NUL)
@@ -6326,19 +6343,19 @@
 	    else if (has_mbyte
 		    && (len < 0 ? ptr[mbyte_blen] == NUL
 					     : ptr + mbyte_blen >= text + len)
-		    && ((mbyte_cells == 1 && (*mb_off2cells)(off) > 1)
+		    && ((mbyte_cells == 1 && (*mb_off2cells)(off, max_off) > 1)
 			|| (mbyte_cells == 2
-			    && (*mb_off2cells)(off) == 1
-			    && (*mb_off2cells)(off + 1) > 1)))
+			    && (*mb_off2cells)(off, max_off) == 1
+			    && (*mb_off2cells)(off + 1, max_off) > 1)))
 		clear_next_cell = TRUE;
 
 	    /* Make sure we never leave a second byte of a double-byte behind,
 	     * it confuses mb_off2cells(). */
 	    if (enc_dbcs
-		    && ((mbyte_cells == 1 && (*mb_off2cells)(off) > 1)
+		    && ((mbyte_cells == 1 && (*mb_off2cells)(off, max_off) > 1)
 			|| (mbyte_cells == 2
-			    && (*mb_off2cells)(off) == 1
-			    && (*mb_off2cells)(off + 1) > 1)))
+			    && (*mb_off2cells)(off, max_off) == 1
+			    && (*mb_off2cells)(off + 1, max_off) > 1)))
 		ScreenLines[off + mbyte_blen] = 0;
 #endif
 	    ScreenLines[off] = c;
@@ -6924,6 +6941,9 @@
 {
     int		r, c;
     int		off;
+#ifdef FEAT_MBYTE
+    int		max_off;
+#endif
 
     /* Can't use ScreenLines unless initialized */
     if (ScreenLines == NULL)
@@ -6934,10 +6954,13 @@
     for (r = row; r < row + height; ++r)
     {
 	off = LineOffset[r];
+#ifdef FEAT_MBYTE
+	max_off = off + screen_Columns;
+#endif
 	for (c = col; c < col + width; ++c)
 	{
 #ifdef FEAT_MBYTE
-	    if (enc_dbcs != 0 && dbcs_off2cells(off + c) > 1)
+	    if (enc_dbcs != 0 && dbcs_off2cells(off + c, max_off) > 1)
 	    {
 		screen_char_2(off + c, r, c);
 		++c;
@@ -6947,7 +6970,7 @@
 	    {
 		screen_char(off + c, r, c);
 #ifdef FEAT_MBYTE
-		if (utf_off2cells(off + c) > 1)
+		if (utf_off2cells(off + c, max_off) > 1)
 		    ++c;
 #endif
 	    }
diff --git a/src/version.c b/src/version.c
index 5137688..1e775e7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -667,6 +667,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    93,
+/**/
     92,
 /**/
     91,