diff --git a/src/swrenderer/scene/r_portal.cpp b/src/swrenderer/scene/r_portal.cpp
index 4d8c04ac41..6c585d13a4 100644
--- a/src/swrenderer/scene/r_portal.cpp
+++ b/src/swrenderer/scene/r_portal.cpp
@@ -527,8 +527,8 @@ namespace swrenderer
 	
 	void RenderPortal::SetMainPortal()
 	{
-		WindowLeft = 0;
-		WindowRight = viewwidth;
+		WindowLeft = Thread->X1;
+		WindowRight = Thread->X2;
 		MirrorFlags = 0;
 		CurrentPortal = nullptr;
 		CurrentPortalUniq = 0;
diff --git a/src/swrenderer/things/r_visiblesprite.cpp b/src/swrenderer/things/r_visiblesprite.cpp
index 8fb1876740..e9ddec275b 100644
--- a/src/swrenderer/things/r_visiblesprite.cpp
+++ b/src/swrenderer/things/r_visiblesprite.cpp
@@ -84,10 +84,6 @@ namespace swrenderer
 		if (x1 >= x2)
 			return;
 
-		// Reject sprites outside the slice rendered by the thread
-		if (x2 < thread->X1 || x1 > thread->X2)
-			return;
-
 		// [RH] Sprites split behind a one-sided line can also be discarded.
 		if (spr->sector == nullptr)
 			return;
diff --git a/src/swrenderer/things/r_voxel.cpp b/src/swrenderer/things/r_voxel.cpp
index fe626dd2fb..a11846abee 100644
--- a/src/swrenderer/things/r_voxel.cpp
+++ b/src/swrenderer/things/r_voxel.cpp
@@ -457,10 +457,7 @@ namespace swrenderer
 					if (voxptr >= voxend) continue;
 
 					lx = xs_RoundToInt(nx * centerxwide_f / (ny + y1)) + viewport->viewwindow.centerx;
-					if (lx < 0) lx = 0;
 					rx = xs_RoundToInt((nx + nxoff) * centerxwide_f / (ny + y2)) + viewport->viewwindow.centerx;
-					if (rx > viewwidth) rx = viewwidth;
-					if (rx <= lx) continue;
 
 					if (flags & DVF_MIRRORED)
 					{
@@ -469,6 +466,10 @@ namespace swrenderer
 						rx = t;
 					}
 
+					if (lx < this->x1) lx = this->x1;
+					if (rx > this->x2) rx = this->x2;
+					if (rx <= lx) continue;
+
 					fixed_t l1 = xs_RoundToInt(centerxwidebig_f / (ny - yoff));
 					fixed_t l2 = xs_RoundToInt(centerxwidebig_f / (ny + yoff));
 					for (; voxptr < voxend; voxptr = (kvxslab_t *)((uint8_t *)voxptr + voxptr->zleng + 3))