diff --git a/src/ops.c b/src/ops.c
index 258b271..b2827b2 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -206,14 +206,15 @@
 	msg((char *)IObuff);
     }
 
-    /*
-     * Set "'[" and "']" marks.
-     */
-    curbuf->b_op_start = oap->start;
-    curbuf->b_op_end.lnum = oap->end.lnum;
-    curbuf->b_op_end.col = (colnr_T)STRLEN(ml_get(oap->end.lnum));
-    if (curbuf->b_op_end.col > 0)
-	--curbuf->b_op_end.col;
+    if (!cmdmod.lockmarks)
+    {
+	// Set "'[" and "']" marks.
+	curbuf->b_op_start = oap->start;
+	curbuf->b_op_end.lnum = oap->end.lnum;
+	curbuf->b_op_end.col = (colnr_T)STRLEN(ml_get(oap->end.lnum));
+	if (curbuf->b_op_end.col > 0)
+	    --curbuf->b_op_end.col;
+    }
 }
 
 /*
@@ -981,14 +982,17 @@
     msgmore(curbuf->b_ml.ml_line_count - old_lcount);
 
 setmarks:
-    if (oap->block_mode)
+    if (!cmdmod.lockmarks)
     {
-	curbuf->b_op_end.lnum = oap->end.lnum;
-	curbuf->b_op_end.col = oap->start.col;
+	if (oap->block_mode)
+	{
+	    curbuf->b_op_end.lnum = oap->end.lnum;
+	    curbuf->b_op_end.col = oap->start.col;
+	}
+	else
+	    curbuf->b_op_end = oap->start;
+	curbuf->b_op_start = oap->start;
     }
-    else
-	curbuf->b_op_end = oap->start;
-    curbuf->b_op_start = oap->start;
 
     return OK;
 }
@@ -1252,9 +1256,12 @@
     check_cursor();
     changed_lines(oap->start.lnum, oap->start.col, oap->end.lnum + 1, 0L);
 
-    /* Set "'[" and "']" marks. */
-    curbuf->b_op_start = oap->start;
-    curbuf->b_op_end = oap->end;
+    if (!cmdmod.lockmarks)
+    {
+	/* Set "'[" and "']" marks. */
+	curbuf->b_op_start = oap->start;
+	curbuf->b_op_end = oap->end;
+    }
 
     return OK;
 }
@@ -1362,11 +1369,12 @@
 	/* No change: need to remove the Visual selection */
 	redraw_curbuf_later(INVERTED);
 
-    /*
-     * Set '[ and '] marks.
-     */
-    curbuf->b_op_start = oap->start;
-    curbuf->b_op_end = oap->end;
+    if (!cmdmod.lockmarks)
+    {
+	// Set '[ and '] marks.
+	curbuf->b_op_start = oap->start;
+	curbuf->b_op_end = oap->end;
+    }
 
     if (oap->line_count > p_report)
 	smsg(NGETTEXT("%ld line changed", "%ld lines changed",
@@ -1973,7 +1981,7 @@
     for (t = 0; t < count; ++t)
     {
 	curr = curr_start = ml_get((linenr_T)(curwin->w_cursor.lnum + t));
-	if (t == 0 && setmark)
+	if (t == 0 && setmark && !cmdmod.lockmarks)
 	{
 	    /* Set the '[ mark. */
 	    curwin->w_buffer->b_op_start.lnum = curwin->w_cursor.lnum;
@@ -2129,7 +2137,7 @@
 #endif
 	ml_replace(curwin->w_cursor.lnum, newp, FALSE);
 
-    if (setmark)
+    if (setmark && !cmdmod.lockmarks)
     {
 	/* Set the '] mark. */
 	curwin->w_buffer->b_op_end.lnum = curwin->w_cursor.lnum;
@@ -2268,8 +2276,9 @@
 	/* When there is no change: need to remove the Visual selection */
 	redraw_curbuf_later(INVERTED);
 
-    /* Set '[ mark at the start of the formatted area */
-    curbuf->b_op_start = oap->start;
+    if (!cmdmod.lockmarks)
+	/* Set '[ mark at the start of the formatted area */
+	curbuf->b_op_start = oap->start;
 
     /* For "gw" remember the cursor position and put it back below (adjusted
      * for joined and split lines). */
@@ -2289,8 +2298,9 @@
     old_line_count = curbuf->b_ml.ml_line_count - old_line_count;
     msgmore(old_line_count);
 
-    /* put '] mark on the end of the formatted area */
-    curbuf->b_op_end = curwin->w_cursor;
+    if (!cmdmod.lockmarks)
+	/* put '] mark on the end of the formatted area */
+	curbuf->b_op_end = curwin->w_cursor;
 
     if (keep_cursor)
     {
@@ -2984,7 +2994,7 @@
 
 	/* Set '[ mark if something changed. Keep the last end
 	 * position from do_addsub(). */
-	if (change_cnt > 0)
+	if (change_cnt > 0 && !cmdmod.lockmarks)
 	    curbuf->b_op_start = startpos;
 
 	if (change_cnt > p_report)
@@ -3384,7 +3394,7 @@
 	    --curwin->w_cursor.col;
     }
 
-    if (did_change)
+    if (did_change && !cmdmod.lockmarks)
     {
 	/* set the '[ and '] marks */
 	curbuf->b_op_start = startpos;
@@ -3905,6 +3915,8 @@
 #ifdef FEAT_EVAL
     typval_T	argv[2];
     int		save_virtual_op = virtual_op;
+    pos_T	orig_start = curbuf->b_op_start;
+    pos_T	orig_end = curbuf->b_op_end;
 
     if (*p_opfunc == NUL)
 	emsg(_("E774: 'operatorfunc' is empty"));
@@ -3933,6 +3945,11 @@
 	(void)call_func_retnr(p_opfunc, 1, argv);
 
 	virtual_op = save_virtual_op;
+	if (cmdmod.lockmarks)
+	{
+	    curbuf->b_op_start = orig_start;
+	    curbuf->b_op_end = orig_end;
+	}
     }
 #else
     emsg(_("E775: Eval feature not available"));