diff --git a/src/g_shared/a_skies.cpp b/src/g_shared/a_skies.cpp
index 57fce23fd0..6e85bd8862 100644
--- a/src/g_shared/a_skies.cpp
+++ b/src/g_shared/a_skies.cpp
@@ -59,13 +59,6 @@ void ASkyViewpoint::BeginPlay ()
 void ASkyViewpoint::Destroy ()
 {
 	// remove all sector references to ourselves.
-	for (int i = 0; i < numsectors; i++)
-	{
-		if (sectors[i].GetPortal(sector_t::floor)->mSkybox == this)
-			sectors[i].ClearPortal(sector_t::floor);
-		if (sectors[i].GetPortal(sector_t::ceiling)->mSkybox == this)
-			sectors[i].ClearPortal(sector_t::ceiling);
-	}
 	for (auto &s : sectorPortals)
 	{
 		if (s.mSkybox == this) s.mSkybox = 0;
diff --git a/src/portal.cpp b/src/portal.cpp
index af98718bfb..64a4dd97de 100644
--- a/src/portal.cpp
+++ b/src/portal.cpp
@@ -231,6 +231,10 @@ FArchive &operator<< (FArchive &arc, FSectorPortal &port)
 		<< port.mDestination
 		<< port.mDisplacement
 		<< port.mPlaneZ;
+	if (arc.IsLoading())
+	{
+		port.mSkybox = nullptr;
+	}
 	return arc;
 }
 
diff --git a/src/portal.h b/src/portal.h
index bba674def5..a87ae207f7 100644
--- a/src/portal.h
+++ b/src/portal.h
@@ -191,7 +191,6 @@ struct FLinePortal
 	double mSinRot;
 	double mCosRot;
 	portnode_t *render_thinglist;
-	void *mRenderData;
 };
 
 extern TArray<FLinePortal> linePortals;
@@ -229,7 +228,6 @@ struct FSectorPortal
 	DVector2 mDisplacement;
 	double mPlaneZ;
 	TObjPtr<AActor> mSkybox;
-	void *mRenderData;
 
 	bool MergeAllowed() const
 	{