diff --git a/libs/models/test/trace-qf-bad.c b/libs/models/test/trace-qf-bad.c
new file mode 100644
index 000000000..b60b3456a
--- /dev/null
+++ b/libs/models/test/trace-qf-bad.c
@@ -0,0 +1,191 @@
+/*
+	trace.c
+
+	BSP line tracing
+
+	Copyright (C) 2004 Bill Currie
+
+	Author: Bill Currie <bill@taniwha.org>
+	Date: 2004/9/25
+
+	This program is free software; you can redistribute it and/or
+	modify it under the terms of the GNU General Public License
+	as published by the Free Software Foundation; either version 2
+	of the License, or (at your option) any later version.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+	See the GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program; if not, write to:
+
+		Free Software Foundation, Inc.
+		59 Temple Place - Suite 330
+		Boston, MA  02111-1307, USA
+
+*/
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+static __attribute__ ((used)) const char rcsid[] =
+	"$Id$";
+
+#ifdef HAVE_STRING_H
+# include <string.h>
+#endif
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif
+
+#include "QF/model.h"
+#include "QF/sys.h"
+
+#include "compat.h"
+#include "world.h"
+
+/* LINE TESTING IN HULLS */
+
+// 1/32 epsilon to keep floating point happy
+#ifndef DIST_EPSILON
+#define	DIST_EPSILON	(0.03125)
+#endif
+
+typedef struct {
+	vec3_t     end;
+	int        side;
+	int        num;
+	mplane_t   *plane;
+} tracestack_t;
+
+static inline void
+calc_impact (trace_t *trace, const vec3_t start, const vec3_t end,
+			 mplane_t *plane)
+{
+	vec_t       t1, t2, frac;
+	vec3_t      dist;
+
+	t1 = PlaneDiff (start, plane);
+	t2 = PlaneDiff (end, plane);
+
+	if (t1 < 0) {
+		frac = (t1 + DIST_EPSILON) / (t1 - t2);
+		// invert plane paramterers
+		VectorNegate (plane->normal, trace->plane.normal);
+		trace->plane.dist = -plane->dist;
+	} else {
+		frac = (t1 - DIST_EPSILON) / (t1 - t2);
+		VectorCopy (plane->normal, trace->plane.normal);
+		trace->plane.dist = plane->dist;
+	}
+	frac = bound (0, frac, 1);
+	trace->fraction = frac;
+	VectorSubtract (end, start, dist);
+	VectorMultAdd (start, frac, dist, trace->endpos);
+}
+
+VISIBLE void
+MOD_TraceLine (hull_t *hull, int num,
+			   const vec3_t start_point, const vec3_t end_point,
+			   trace_t *trace)
+{
+	vec_t       start_dist, end_dist, frac;
+	vec3_t      start, end, dist;
+	int         side, empty, solid;
+	tracestack_t *tstack;
+	tracestack_t tracestack[256];
+	mclipnode_t *node;
+	mplane_t   *plane, *split_plane;
+
+	VectorCopy (start_point, start);
+	VectorCopy (end_point, end);
+
+	tstack = tracestack;
+	empty = 0;
+	solid = 0;
+	split_plane = 0;
+
+	while (1) {
+		while (num < 0) {
+			if (!solid && num != CONTENTS_SOLID) {
+				empty = 1;
+				if (num == CONTENTS_EMPTY)
+					trace->inopen = true;
+				else
+					trace->inwater = true;
+			} else if (!empty && num == CONTENTS_SOLID) {
+				solid = 1;
+			} else if (solid && num != CONTENTS_SOLID) {
+				//FIXME not sure what I want
+				//made it out of the solid and into open space, continue
+				//on as if we were always in empty space
+				empty = 1;
+				solid = 0;
+				trace->startsolid = 1;
+				if (num == CONTENTS_EMPTY)
+					trace->inopen = true;
+				else
+					trace->inwater = true;
+			} else if (empty/* || solid*/) {//FIXME not sure what I want
+				// DONE!
+				trace->allsolid = solid & (num == CONTENTS_SOLID);
+				trace->startsolid = solid;
+				calc_impact (trace, start_point, end_point, split_plane);
+				return;
+			}
+
+			// pop up the stack for a back side
+			if (tstack-- == tracestack) {
+				// we've finished.
+				trace->allsolid = solid & (num == CONTENTS_SOLID);
+				trace->startsolid = solid;
+				return;
+			}
+
+			// set the hit point for this plane
+			VectorCopy (end, start);
+
+			// go down the back side
+			VectorCopy (tstack->end, end);
+			side = tstack->side;
+			split_plane = tstack->plane;
+
+			num = hull->clipnodes[tstack->num].children[side ^ 1];
+		}
+
+		node = hull->clipnodes + num;
+		plane = hull->planes + node->planenum;
+
+		start_dist = PlaneDiff (start, plane);
+		end_dist = PlaneDiff (end, plane);
+
+		if (start_dist >= 0 && end_dist >= 0) {
+			// entirely in front of the plane
+			num = node->children[0];
+			continue;
+		}
+		if (start_dist < 0 && end_dist < 0) {
+			// entirely behind the plane
+			num = node->children[1];
+			continue;
+		}
+
+		side = start_dist < 0;
+		frac = start_dist / (start_dist - end_dist);
+		frac = bound (0, frac, 1);
+
+		tstack->num = num;
+		tstack->side = side;
+		tstack->plane = plane;
+		VectorCopy (end, tstack->end);
+		tstack++;
+
+		VectorSubtract (end, start, dist);
+		VectorMultAdd (start, frac, dist, end);
+
+		num = node->children[side];
+	}
+}