diff --git a/src/rendering/hwrenderer/doom_levelmesh.cpp b/src/rendering/hwrenderer/doom_levelmesh.cpp
index e47c27c0b..da7c6a79e 100644
--- a/src/rendering/hwrenderer/doom_levelmesh.cpp
+++ b/src/rendering/hwrenderer/doom_levelmesh.cpp
@@ -470,7 +470,7 @@ void DoomLevelMesh::CreateSideSurfaces(FLevelLocals &doomMap, side_t *side)
 		MeshVertices.Push(verts[2]);
 		MeshVertices.Push(verts[3]);
 
-		surf.plane = ToPlane(verts[0], verts[1], verts[2]);
+		surf.plane = ToPlane(verts[0], verts[1], verts[2], verts[3]);
 		Surfaces.Push(surf);
 		return;
 	}
@@ -501,7 +501,7 @@ void DoomLevelMesh::CreateSideSurfaces(FLevelLocals &doomMap, side_t *side)
 		MeshVertices.Push(verts[2]);
 		MeshVertices.Push(verts[3]);
 
-		surf.plane = ToPlane(verts[0], verts[1], verts[2]);
+		surf.plane = ToPlane(verts[0], verts[1], verts[2], verts[3]);
 		Surfaces.Push(surf);
 		return;
 	}
@@ -549,7 +549,7 @@ void DoomLevelMesh::CreateSideSurfaces(FLevelLocals &doomMap, side_t *side)
 			MeshVertices.Push(verts[2]);
 			MeshVertices.Push(verts[3]);
 
-			surf.plane = ToPlane(verts[0], verts[1], verts[2]);
+			surf.plane = ToPlane(verts[0], verts[1], verts[2], verts[3]);
 			Surfaces.Push(surf);
 		}
 
@@ -587,7 +587,7 @@ void DoomLevelMesh::CreateSideSurfaces(FLevelLocals &doomMap, side_t *side)
 				MeshVertices.Push(verts[2]);
 				MeshVertices.Push(verts[3]);
 
-				surf.plane = ToPlane(verts[0], verts[1], verts[2]);
+				surf.plane = ToPlane(verts[0], verts[1], verts[2], verts[3]);
 				surf.Type = ST_LOWERSIDE;
 				surf.typeIndex = typeIndex;
 				surf.bSky = false;
@@ -626,7 +626,7 @@ void DoomLevelMesh::CreateSideSurfaces(FLevelLocals &doomMap, side_t *side)
 				MeshVertices.Push(verts[2]);
 				MeshVertices.Push(verts[3]);
 
-				surf.plane = ToPlane(verts[0], verts[1], verts[2]);
+				surf.plane = ToPlane(verts[0], verts[1], verts[2], verts[3]);
 				surf.Type = ST_UPPERSIDE;
 				surf.typeIndex = typeIndex;
 				surf.bSky = bSky;
@@ -665,7 +665,7 @@ void DoomLevelMesh::CreateSideSurfaces(FLevelLocals &doomMap, side_t *side)
 		MeshVertices.Push(verts[2]);
 		MeshVertices.Push(verts[3]);
 
-		surf.plane = ToPlane(verts[0], verts[1], verts[2]);
+		surf.plane = ToPlane(verts[0], verts[1], verts[2], verts[3]);
 		surf.Type = ST_MIDDLESIDE;
 		surf.typeIndex = typeIndex;
 		surf.sampleDimension = side->textures[side_t::mid].LightmapSampleDistance;
diff --git a/src/rendering/hwrenderer/doom_levelmesh.h b/src/rendering/hwrenderer/doom_levelmesh.h
index 603a0f240..1de70b7c5 100644
--- a/src/rendering/hwrenderer/doom_levelmesh.h
+++ b/src/rendering/hwrenderer/doom_levelmesh.h
@@ -78,6 +78,20 @@ private:
 		return FVector4(n.X, n.Y, n.Z, d);
 	}
 
+	static FVector4 ToPlane(const FVector3& pt1, const FVector3& pt2, const FVector3& pt3, const FVector3& pt4)
+	{
+		if (pt1.ApproximatelyEquals(pt3))
+		{
+			return ToPlane(pt1, pt2, pt4);
+		}
+		else if(pt1.ApproximatelyEquals(pt2) || pt2.ApproximatelyEquals(pt3))
+		{
+			return ToPlane(pt1, pt3, pt4);
+		}
+
+		return ToPlane(pt1, pt2, pt3);
+	}
+
 	static FVector2 ToFVector2(const DVector2& v) { return FVector2((float)v.X, (float)v.Y); }
 	static FVector3 ToFVector3(const DVector3& v) { return FVector3((float)v.X, (float)v.Y, (float)v.Z); }
 	static FVector4 ToFVector4(const DVector4& v) { return FVector4((float)v.X, (float)v.Y, (float)v.Z, (float)v.W); }