diff --git a/src/treesit.c b/src/treesit.c
index 93ed97212d7..879405e551a 100644
--- a/src/treesit.c
+++ b/src/treesit.c
@@ -931,7 +931,10 @@ treesit_sync_visible_region (Lisp_Object parser)
      this function is called), we need to reparse.  */
   if (visible_beg != BUF_BEGV_BYTE (buffer)
       || visible_end != BUF_ZV_BYTE (buffer))
-    XTS_PARSER (parser)->need_reparse = true;
+    {
+      XTS_PARSER (parser)->need_reparse = true;
+      XTS_PARSER (parser)->timestamp++;
+    }
 
   /* Before we parse or set ranges, catch up with the narrowing
      situation.  We change visible_beg and visible_end to match
@@ -1671,6 +1674,7 @@ buffer.  */)
 	      ranges);
 
   XTS_PARSER (parser)->need_reparse = true;
+  XTS_PARSER (parser)->timestamp++;
   return Qnil;
 }
 
diff --git a/src/treesit.h b/src/treesit.h
index 5382bc58817..3d59262b53a 100644
--- a/src/treesit.h
+++ b/src/treesit.h
@@ -53,7 +53,9 @@ struct Lisp_TS_Parser
   /* Re-parsing an unchanged buffer is not free for tree-sitter, so we
      only make it re-parse when need_reparse == true.  That usually
      means some change is made in the buffer.  But others could set
-     this field to true to force tree-sitter to re-parse.  */
+     this field to true to force tree-sitter to re-parse.  When you
+     set this to true, you should _always_ also increment
+     timestamp.  */
   bool need_reparse;
   /* These two positions record the buffer byte position (1-based) of
      the "visible region" that tree-sitter sees.  Before re-parse, we