diff --git a/src/gl/scene/gl_drawinfo.cpp b/src/gl/scene/gl_drawinfo.cpp
index ac009a1c3..ecbbac0b7 100644
--- a/src/gl/scene/gl_drawinfo.cpp
+++ b/src/gl/scene/gl_drawinfo.cpp
@@ -48,6 +48,7 @@
 #include "gl/renderer/gl_quaddrawer.h"
 
 FDrawInfo * gl_drawinfo;
+FDrawInfoList di_list;
 
 //==========================================================================
 //
@@ -987,8 +988,6 @@ void FDrawInfoList::Release(FDrawInfo * di)
 	mList.Push(di);
 }
 
-static FDrawInfoList di_list;
-
 //==========================================================================
 //
 //
diff --git a/src/gl/scene/gl_portal.cpp b/src/gl/scene/gl_portal.cpp
index 09aba32e1..130fb263a 100644
--- a/src/gl/scene/gl_portal.cpp
+++ b/src/gl/scene/gl_portal.cpp
@@ -87,6 +87,8 @@ UniqueList<GLHorizonInfo> UniqueHorizons;
 UniqueList<secplane_t> UniquePlaneMirrors;
 UniqueList<FLinePortalSpan> UniqueLineToLines;
 
+int skyboxrecursion = 0;
+
 //==========================================================================
 //
 //
@@ -460,7 +462,7 @@ void GLPortal::StartFrame()
 
 //-----------------------------------------------------------------------------
 //
-// Portal info
+// printing portal info
 //
 //-----------------------------------------------------------------------------
 
@@ -471,7 +473,7 @@ CCMD(gl_portalinfo)
 	gl_portalinfo = true;
 }
 
-FString indent;
+static FString indent;
 
 //-----------------------------------------------------------------------------
 //
@@ -610,7 +612,7 @@ void GLPortal::RestoreMapSection()
 // GLSkyboxPortal::DrawContents
 //
 //-----------------------------------------------------------------------------
-static int skyboxrecursion=0;
+
 void GLSkyboxPortal::DrawContents()
 {
 	int old_pm = PlaneMirrorMode;
diff --git a/src/gl/scene/gl_renderhacks.cpp b/src/gl/scene/gl_renderhacks.cpp
index d1e50ee92..fff839c5e 100644
--- a/src/gl/scene/gl_renderhacks.cpp
+++ b/src/gl/scene/gl_renderhacks.cpp
@@ -44,9 +44,16 @@
 // profiling data
 static int totalupper, totallower;
 static int lowershcount, uppershcount;
-static glcycle_t totalms, showtotalms;
-static glcycle_t totalssms;
-static sector_t fakesec;
+static glcycle_t totalms, showtotalms, totalssms;
+
+
+static sector_t fakesec;	// this is static because it gets used in recursively called functions.
+
+// Having this static doesn't really matter here because the hack code is not multithreading-capable anyway.
+static bool inview;
+static subsector_t * viewsubsector;
+static TArray<seg_t *> lowersegs;
+
 
 void FDrawInfo::ClearBuffers()
 {
@@ -760,9 +767,6 @@ bool FDrawInfo::CheckAnchorFloor(subsector_t * sub)
 // Collect connected subsectors that have to be rendered with the same plane
 //
 //==========================================================================
-static bool inview;
-static subsector_t * viewsubsector;
-static TArray<seg_t *> lowersegs;
 
 bool FDrawInfo::CollectSubsectorsFloor(subsector_t * sub, sector_t * anchor)
 {
@@ -1117,12 +1121,11 @@ void FDrawInfo::CollectSectorStacksFloor(subsector_t * sub, sector_t * anchor)
 void FDrawInfo::ProcessSectorStacks()
 {
 	unsigned int i;
-	sector_t fake;
 
 	validcount++;
 	for (i=0;i<CeilingStacks.Size (); i++)
 	{
-		sector_t *sec = gl_FakeFlat(CeilingStacks[i], &fake, mDrawer->in_area, false);
+		sector_t *sec = gl_FakeFlat(CeilingStacks[i], &fakesec, mDrawer->in_area, false);
 		auto portal = sec->GetPortalGroup(sector_t::ceiling);
 		if (portal != NULL) for(int k=0;k<sec->subsectorcount;k++)
 		{
@@ -1147,7 +1150,7 @@ void FDrawInfo::ProcessSectorStacks()
 
 					if (sub->portalcoverage[sector_t::ceiling].subsectors == NULL)
 					{
-						BuildPortalCoverage(&sub->portalcoverage[sector_t::ceiling],	sub, portal->mDisplacement);
+						BuildPortalCoverage(&sub->portalcoverage[sector_t::ceiling], sub, portal->mDisplacement);
 					}
 
 					portal->GetRenderState()->AddSubsector(sub);
@@ -1166,7 +1169,7 @@ void FDrawInfo::ProcessSectorStacks()
 	validcount++;
 	for (i=0;i<FloorStacks.Size (); i++)
 	{
-		sector_t *sec = gl_FakeFlat(FloorStacks[i], &fake, mDrawer->in_area, false);
+		sector_t *sec = gl_FakeFlat(FloorStacks[i], &fakesec, mDrawer->in_area, false);
 		auto portal = sec->GetPortalGroup(sector_t::floor);
 		if (portal != NULL) for(int k=0;k<sec->subsectorcount;k++)
 		{
diff --git a/src/gl/scene/gl_scene.cpp b/src/gl/scene/gl_scene.cpp
index 7437816d2..8c5d9f7ad 100644
--- a/src/gl/scene/gl_scene.cpp
+++ b/src/gl/scene/gl_scene.cpp
@@ -86,8 +86,7 @@ EXTERN_CVAR (Bool, r_drawvoxels)
 
 extern bool NoInterpolateView;
 
-area_t			in_area;
-int camtexcount;
+int camtexcount;	// used to decide how VSync is done. It just counts the number of camera textures per frame.
 
 //-----------------------------------------------------------------------------
 //
@@ -273,7 +272,9 @@ void GLSceneDrawer::CreateScene()
 	if (GLRenderer->mCurrentPortal != NULL) GLRenderer->mCurrentPortal->RenderAttached();
 	Bsp.Unclock();
 
-	// And now the crappy hacks that have to be done to avoid rendering anomalies:
+	// And now the crappy hacks that have to be done to avoid rendering anomalies.
+	// These cannot be multithreaded when the time comes because all these depend
+	// on the global 'validcount' variable.
 
 	gl_drawinfo->HandleMissingTextures();	// Missing upper/lower textures
 	gl_drawinfo->HandleHackedSubsectors();	// open sector hacks for deep water
diff --git a/src/gl/scene/gl_scenedrawer.h b/src/gl/scene/gl_scenedrawer.h
index 4f59120ac..c926d0aae 100644
--- a/src/gl/scene/gl_scenedrawer.h
+++ b/src/gl/scene/gl_scenedrawer.h
@@ -56,6 +56,7 @@ public:
 	int		FixedColormap;
 	area_t	in_area;
 	BitArray CurrentMapSections;	// this cannot be a single number, because a group of portals with the same displacement may link different sections.
+	FDrawInfo * gl_drawinfo;
 
 	angle_t FrustumAngle();
 	void SetViewMatrix(float vx, float vy, float vz, bool mirror, bool planemirror);