diff --git a/Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySector.cs b/Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySector.cs
index d8458df8..84a02257 100644
--- a/Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySector.cs
+++ b/Source/Plugins/BuilderModes/VisualModes/BaseVisualGeometrySector.cs
@@ -95,6 +95,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		// This changes the height
 		protected abstract void ChangeHeight(int amount);
 		protected abstract void ChangeTextureScale(int incrementX, int incrementY); //mxd
+		protected abstract void UpdateSkyRenderFlag(); //mxd
 		public virtual void SelectNeighbours(bool select, bool withSameTexture, bool withSameHeight) { } //mxd
 
 		// This swaps triangles so that the plane faces the other way
@@ -218,14 +219,17 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		//mxd
 		protected void OnTextureChanged() 
 		{
-			//mxd. Effects may need updating...
+			// Effects may need updating...
 			mode.RebuildElementData();
+
+			// As well as sky render flag...
+			UpdateSkyRenderFlag();
 			
 			if(level.sector == this.Sector.Sector) 
 			{
 				this.Setup();
 
-				//mxd. 3D floors may need updating...
+				// 3D floors may need updating...
 				foreach(Sidedef s in level.sector.Sidedefs) 
 				{
 					if(s.Line.Action == 160 && s.Line.Front != null) 
@@ -242,7 +246,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					}
 				}
 			}
-			//mxd. As well as this sector's geometry
+			// As well as this sector's geometry
 			else if(mode.VisualSectorExists(level.sector)) 
 			{
 				BaseVisualSector vs = (BaseVisualSector)mode.GetVisualSector(level.sector);
diff --git a/Source/Plugins/BuilderModes/VisualModes/VisualCeiling.cs b/Source/Plugins/BuilderModes/VisualModes/VisualCeiling.cs
index 983542a9..d6c5ebca 100644
--- a/Source/Plugins/BuilderModes/VisualModes/VisualCeiling.cs
+++ b/Source/Plugins/BuilderModes/VisualModes/VisualCeiling.cs
@@ -198,7 +198,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		}
 
 		//mxd
-		private void UpdateSkyRenderFlag()
+		protected override void UpdateSkyRenderFlag()
 		{
 			bool isrenderedassky = renderassky;
 			renderassky = (level.sector.CeilTexture == General.Map.Config.SkyFlatName);
@@ -210,6 +210,18 @@ namespace CodeImp.DoomBuilder.BuilderModes
 					VisualSidedefParts parts = Sector.GetSidedefParts(side);
 					if(parts.upper != null) parts.upper.UpdateSkyRenderFlag();
 					else if(parts.middlesingle != null) parts.middlesingle.UpdateSkyRenderFlag();
+
+					// On the other side as well...
+					if(side.Other != null && side.Other.Sector != null &&
+					   side.Other.Sector.CeilTexture == General.Map.Config.SkyFlatName)
+					{
+						BaseVisualSector other = (BaseVisualSector)mode.GetVisualSector(side.Other.Sector);
+						if(other != null && other.Sides != null)
+						{
+							parts = other.GetSidedefParts(side.Other);
+							if(parts.upper != null) parts.upper.UpdateSkyRenderFlag();
+						}
+					}
 				}
 			}
 		}
diff --git a/Source/Plugins/BuilderModes/VisualModes/VisualFloor.cs b/Source/Plugins/BuilderModes/VisualModes/VisualFloor.cs
index 1e0ec9c3..4ae95cfa 100644
--- a/Source/Plugins/BuilderModes/VisualModes/VisualFloor.cs
+++ b/Source/Plugins/BuilderModes/VisualModes/VisualFloor.cs
@@ -200,7 +200,7 @@ namespace CodeImp.DoomBuilder.BuilderModes
 		}
 
 		//mxd
-		private void UpdateSkyRenderFlag()
+		protected override void UpdateSkyRenderFlag()
 		{
 			bool isrenderedassky = renderassky;
 			renderassky = (level.sector.FloorTexture == General.Map.Config.SkyFlatName || level.sector.LongFloorTexture == MapSet.EmptyLongName);