diff --git a/include/world.h b/include/world.h
index 0b9bf1b06..81d053833 100644
--- a/include/world.h
+++ b/include/world.h
@@ -123,6 +123,7 @@ typedef struct clipport_s {
 	struct clipport_s *next[2];		///< front, back
 	struct clipleaf_s *leafs[2];	///< front, back
 	struct winding_s *winding;
+	struct winding_s *edges;		///< unit vectors along edges
 } clipport_t;
 
 typedef struct clipleaf_s {
diff --git a/libs/models/portal.c b/libs/models/portal.c
index 21678d5ce..f6d312ff9 100644
--- a/libs/models/portal.c
+++ b/libs/models/portal.c
@@ -171,11 +171,27 @@ nodeleaf_t *
 MOD_BuildBrushes (hull_t *hull)
 {
 	int         numnodes = hull->lastclipnode + 1;
+	int         i, j, side;
 	nodeleaf_t *nodeleafs;
 	clipleaf_t *root;		// this will be carved into all the actual leafs
 
 	nodeleafs = calloc (numnodes, sizeof (nodeleaf_t));
 	root = alloc_leaf ();
 	carve_leaf (hull, nodeleafs, root, hull->firstclipnode);
+	for (i = 0; i < numnodes; i++) {
+		for (j = 0; j < 2; j++) {
+			clipleaf_t *leaf = nodeleafs[i].leafs[j];
+			clipport_t *p;
+
+			if (!leaf)
+				continue;
+			for (p = leaf->portals; p; p = p->next[side]) {
+				side = p->leafs[1] == leaf;
+				if (p->edges)
+					continue;
+				p->edges = WindingVectors (p->winding);
+			}
+		}
+	}
 	return nodeleafs;
 }
diff --git a/libs/models/test/testclip.c b/libs/models/test/testclip.c
index cbfeb4e34..c9b89276d 100644
--- a/libs/models/test/testclip.c
+++ b/libs/models/test/testclip.c
@@ -451,8 +451,14 @@ run_test (test_t *test)
 				portal_list = collect_portals (leaf->portals, portal_list);
 			}
 		}
-		for (i = 0, p = portal_list; p; i++, p = p->next)
-			;
+		for (i = 0, p = portal_list; p; i++, p = p->next) {
+			if (!p->portal->winding || !p->portal->edges) {
+				res = 1;
+				printf ("portal with missing vertex/edge information\n");
+			}
+		}
+		if (res)
+			goto nodeleaf_bail;
 		if (i != test->expect.num_portals) {
 			res = 1;
 			printf ("bad portal count: %d %d\n", test->expect.num_portals, i);