diff --git a/binaries/data/mods/official/maps/scenario_v4.dtd b/binaries/data/mods/official/maps/scenario_v4.dtd
index 7fa8f3b431..990621c18f 100644
--- a/binaries/data/mods/official/maps/scenario_v4.dtd
+++ b/binaries/data/mods/official/maps/scenario_v4.dtd
@@ -1,6 +1,6 @@
 <!ELEMENT Scenario (Environment,Entities,Nonentities)>
 
-	<!ELEMENT Environment (SunColour,SunElevation,SunRotation,TerrainAmbientColour,UnitsAmbientColour,TerrainShadowTransparency)>
+	<!ELEMENT Environment (SunColour,SunElevation,SunRotation,TerrainAmbientColour,UnitsAmbientColour,TerrainShadowTransparency?)>
 	
 		<!ELEMENT SunColour EMPTY>
 		<!ATTLIST SunColour