diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index 60d7202..53334342 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -673,12 +673,17 @@
     long	vcol;
     long	start_col = 0;		/* For start of white-space string */
     long	start_vcol = 0;		/* For start of white-space string */
-    int		temp;
     long	old_len;
     char_u	*ptr;
     char_u	*new_line = (char_u *)1;    /* init to non-NULL */
     int		did_undo;		/* called u_save for current line */
+#ifdef FEAT_VARTABS
+    int		*new_ts = 0;
+    char_u	*new_ts_str;		/* string value of tab argument */
+#else
+    int		temp;
     int		new_ts;
+#endif
     int		save_list;
     linenr_T	first_line = 0;		/* first changed line */
     linenr_T	last_line = 0;		/* last changed line */
@@ -686,6 +691,23 @@
     save_list = curwin->w_p_list;
     curwin->w_p_list = 0;	    /* don't want list mode here */
 
+#ifdef FEAT_VARTABS
+    new_ts_str = eap->arg;
+    if (!tabstop_set(eap->arg, &new_ts))
+	return;
+    while (vim_isdigit(*(eap->arg)) || *(eap->arg) == ',')
+	++(eap->arg);
+
+    // This ensures that either new_ts and new_ts_str are freshly allocated,
+    // or new_ts points to an existing array and new_ts_str is null.
+    if (new_ts == 0)
+    {
+	new_ts = curbuf->b_p_vts_array;
+	new_ts_str = NULL;
+    }
+    else
+	new_ts_str = vim_strnsave(new_ts_str, eap->arg - new_ts_str);
+#else
     new_ts = getdigits(&(eap->arg));
     if (new_ts < 0)
     {
@@ -694,6 +716,7 @@
     }
     if (new_ts == 0)
 	new_ts = curbuf->b_p_ts;
+#endif
     for (lnum = eap->line1; !got_int && lnum <= eap->line2; ++lnum)
     {
 	ptr = ml_get(lnum);
@@ -726,6 +749,16 @@
 		    num_tabs = 0;
 		    if (!curbuf->b_p_et)
 		    {
+#ifdef FEAT_VARTABS
+			int t, s;
+
+			tabstop_fromto(start_vcol, vcol,
+				       tabstop_count(new_ts)? 0: curbuf->b_p_ts,
+				       new_ts,
+				       &t, &s);
+			num_tabs = t;
+			num_spaces = s;
+#else
 			temp = new_ts - (start_vcol % new_ts);
 			if (num_spaces >= temp)
 			{
@@ -734,6 +767,7 @@
 			}
 			num_tabs += num_spaces / new_ts;
 			num_spaces -= (num_spaces / new_ts) * new_ts;
+#endif
 		    }
 		    if (curbuf->b_p_et || got_tab ||
 					(num_spaces + num_tabs < len))
@@ -791,14 +825,53 @@
     if (got_int)
 	EMSG(_(e_interr));
 
+#ifdef FEAT_VARTABS
+    // If a single value was given then it can be considered equal to
+    // either the value of 'tabstop' or the value of 'vartabstop'.
+    if (tabstop_count(curbuf->b_p_vts_array) == 0
+	&& tabstop_count(new_ts) == 1
+	&& curbuf->b_p_ts == tabstop_first(new_ts))
+	; /* not changed */
+    else if (tabstop_count(curbuf->b_p_vts_array) > 0
+        && tabstop_eq(curbuf->b_p_vts_array, new_ts))
+	; /* not changed */
+    else
+	redraw_curbuf_later(NOT_VALID);
+#else
     if (curbuf->b_p_ts != new_ts)
 	redraw_curbuf_later(NOT_VALID);
+#endif
     if (first_line != 0)
 	changed_lines(first_line, 0, last_line + 1, 0L);
 
     curwin->w_p_list = save_list;	/* restore 'list' */
 
+#ifdef FEAT_VARTABS
+    if (new_ts_str != NULL)		/* set the new tabstop */
+    {
+	// If 'vartabstop' is in use or if the value given to retab has more
+	// than one tabstop then update 'vartabstop'.
+	int *old_vts_ary = curbuf->b_p_vts_array;
+
+	if (tabstop_count(old_vts_ary) > 0 || tabstop_count(new_ts) > 1)
+	{
+	    set_string_option_direct((char_u *)"vts", -1, new_ts_str,
+							OPT_FREE|OPT_LOCAL, 0);
+	    vim_free(new_ts_str);
+	    curbuf->b_p_vts_array = new_ts;
+	    vim_free(old_vts_ary);
+	}
+	else
+	{
+	    // 'vartabstop' wasn't in use and a single value was given to
+	    // retab then update 'tabstop'.
+	    curbuf->b_p_ts = tabstop_first(new_ts);
+	    vim_free(new_ts);
+	}
+    }
+#else
     curbuf->b_p_ts = new_ts;
+#endif
     coladvance(curwin->w_curswant);
 
     u_clearline();