diff --git a/include/qbsp/winding.hh b/include/qbsp/winding.hh
index 46d85137..c150a16d 100644
--- a/include/qbsp/winding.hh
+++ b/include/qbsp/winding.hh
@@ -38,6 +38,7 @@ winding_t *BaseWindingForPlane(const qbsp_plane_t *p);
 void CheckWinding(const winding_t *w);
 winding_t *NewWinding(int points);
 winding_t *CopyWinding(const winding_t *w);
+winding_t *FlipWinding(const winding_t *w);
 winding_t *ClipWinding(winding_t *in, const qbsp_plane_t *split, bool keepon);
 void DivideWinding(const winding_t *in, const qbsp_plane_t *split, winding_t **front,
                    winding_t **back);
diff --git a/qbsp/winding.cc b/qbsp/winding.cc
index 8d5a45c6..80a5b291 100644
--- a/qbsp/winding.cc
+++ b/qbsp/winding.cc
@@ -112,7 +112,19 @@ CopyWinding(const winding_t *w)
     return c;
 }
 
-
+/*
+==================
+FlipWinding
+==================
+*/
+winding_t *FlipWinding(const winding_t *w)
+{
+    winding_t *result = CopyWinding(w);
+    for (int i=0; i<w->numpoints; i++) {
+        VectorCopy(w->points[i], result->points[w->numpoints - 1 - i]);
+    }
+    return result;
+}
 
 /*
 ==================