diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index 36ff86abd..c650ecb51 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -582,10 +582,26 @@ static void HWR_RenderPlane(subsector_t *subsector, extrasubsector_t *xsub, bool
 				P_ClosestPointOnLine(viewx, viewy, line->linedef, &v);
 				dist = FIXED_TO_FLOAT(R_PointToDist(v.x, v.y));
 
-				x1 = ((polyvertex_t *)line->pv1)->x;
-				y1 = ((polyvertex_t *)line->pv1)->y;
-				xd = ((polyvertex_t *)line->pv2)->x - x1;
-				yd = ((polyvertex_t *)line->pv2)->y - y1;
+				if (line->pv1)
+				{
+					x1 = ((polyvertex_t *)line->pv1)->x;
+					y1 = ((polyvertex_t *)line->pv1)->y;
+				}
+				else
+				{
+					x1 = FIXED_TO_FLOAT(line->v1->x);
+					y1 = FIXED_TO_FLOAT(line->v1->x);
+				}
+				if (line->pv2)
+				{
+					xd = ((polyvertex_t *)line->pv2)->x - x1;
+					yd = ((polyvertex_t *)line->pv2)->y - y1;
+				}
+				else
+				{
+					xd = FIXED_TO_FLOAT(line->v2->x) - x1;
+					yd = FIXED_TO_FLOAT(line->v2->y) - y1;
+				}
 
 				// Based on the seg length and the distance from the line, split horizon into multiple poly sets to reduce distortion
 				dist = sqrtf((xd*xd) + (yd*yd)) / dist / 16.0f;
@@ -1068,10 +1084,26 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 	gl_sidedef = gl_curline->sidedef;
 	gl_linedef = gl_curline->linedef;
 
-	vs.x = ((polyvertex_t *)gl_curline->pv1)->x;
-	vs.y = ((polyvertex_t *)gl_curline->pv1)->y;
-	ve.x = ((polyvertex_t *)gl_curline->pv2)->x;
-	ve.y = ((polyvertex_t *)gl_curline->pv2)->y;
+	if (gl_curline->pv1)
+	{
+		vs.x = ((polyvertex_t *)gl_curline->pv1)->x;
+		vs.y = ((polyvertex_t *)gl_curline->pv1)->y;
+	}
+	else
+	{
+		vs.x = FIXED_TO_FLOAT(gl_curline->v1->x);
+		vs.y = FIXED_TO_FLOAT(gl_curline->v1->y);
+	}
+	if (gl_curline->pv2)
+	{
+		ve.x = ((polyvertex_t *)gl_curline->pv2)->x;
+		ve.y = ((polyvertex_t *)gl_curline->pv2)->y;
+	}
+	else
+	{
+		ve.x = FIXED_TO_FLOAT(gl_curline->v2->x);
+		ve.y = FIXED_TO_FLOAT(gl_curline->v2->y);
+	}
 
 	v1x = FLOAT_TO_FIXED(vs.x);
 	v1y = FLOAT_TO_FIXED(vs.y);
@@ -1866,10 +1898,26 @@ static boolean CheckClip(seg_t * seg, sector_t * afrontsector, sector_t * abacks
 	if (afrontsector->f_slope || afrontsector->c_slope || abacksector->f_slope || abacksector->c_slope)
 	{
 		fixed_t v1x, v1y, v2x, v2y; // the seg's vertexes as fixed_t
-		v1x = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv1)->x);
-		v1y = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv1)->y);
-		v2x = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv2)->x);
-		v2y = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv2)->y);
+		if (gl_curline->pv1)
+		{
+			v1x = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv1)->x);
+			v1y = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv1)->y);
+		}
+		else
+		{
+			v1x = gl_curline->v1->x;
+			v1y = gl_curline->v1->y;
+		}
+		if (gl_curline->pv2)
+		{
+			v2x = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv2)->x);
+			v2y = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv2)->y);
+		}
+		else
+		{
+			v2x = gl_curline->v2->x;
+			v2y = gl_curline->v2->y;
+		}
 #define SLOPEPARAMS(slope, end1, end2, normalheight) \
 		end1 = P_GetZAt(slope, v1x, v1y, normalheight); \
 		end2 = P_GetZAt(slope, v2x, v2y, normalheight);
@@ -2242,10 +2290,26 @@ static void HWR_AddLine(seg_t * line)
 
 	gl_curline = line;
 
-	v1x = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv1)->x);
-	v1y = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv1)->y);
-	v2x = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv2)->x);
-	v2y = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv2)->y);
+	if (gl_curline->pv1)
+	{
+		v1x = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv1)->x);
+		v1y = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv1)->y);
+	}
+	else
+	{
+		v1x = gl_curline->v1->x;
+		v1y = gl_curline->v1->y;
+	}
+	if (gl_curline->pv2)
+	{
+		v2x = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv2)->x);
+		v2y = FLOAT_TO_FIXED(((polyvertex_t *)gl_curline->pv2)->y);
+	}
+	else
+	{
+		v2x = gl_curline->v2->x;
+		v2y = gl_curline->v2->y;
+	}
 
 	// OPTIMIZE: quickly reject orthogonal back sides.
 	angle1 = R_PointToAngle64(v1x, v1y);