diff --git a/changelog.md b/changelog.md
index b77e36e5363..b4868ab2c2e 100644
--- a/changelog.md
+++ b/changelog.md
@@ -48,6 +48,7 @@
    * [effect]apply_to=variation now supports heal_full
    * Support [set/clear_variable] inside [modify_unit/side]
    * Support [variables] in [modify_side], as in [modify_unit]
+   * [modify_unit] now accepts rebuild=no which will avoid a rebuild of the unit if possible (not guaranteed)
  ### Packaging
    * The Wesnoth client now looks for the data/dist file when logging into the multiplayer server.
      This file should contain one of the following values based on where the package is for:
diff --git a/data/lua/wml/modify_unit.lua b/data/lua/wml/modify_unit.lua
index c704445922c..e1bfc6fb356 100644
--- a/data/lua/wml/modify_unit.lua
+++ b/data/lua/wml/modify_unit.lua
@@ -53,6 +53,7 @@ local known_attributes = make_set {
 	"description",
 	"hidden",
 	"unrenamable",
+	"rebuild",
 }
 
 local known_tags = make_set {
@@ -179,9 +180,11 @@ local function simple_modify_unit(cfg)
 			u:transform(cfg.type or u.type, cfg.variation)
 		end
 
-		-- always do an advancement here (not only when experience/max_experience/type was modified)
-		-- for compatability with old code.
-		u:advance()
+		-- by default always do an advancement here (not only when experience/max_experience/type was modified)
+		-- for compatibility with old code.
+		if cfg.experience or cfg.max_experience or cfg.rebuild ~= false then
+			u:advance()
+		end
 	end
 
 	local this_unit = utils.start_var_scope("this_unit")