diff --git a/cruft/util/geom/segment.cpp b/cruft/util/geom/segment.cpp
index 3e000bd1..df1c288b 100644
--- a/cruft/util/geom/segment.cpp
+++ b/cruft/util/geom/segment.cpp
@@ -70,6 +70,7 @@ cruft::geom::intersects (cruft::geom::segment2i seg, cruft::region2i rect)
 
 
 ///////////////////////////////////////////////////////////////////////////////
+// Not-inclusive
 template <>
 bool
 cruft::geom::intersects (cruft::geom::segment2f ab, cruft::point2f p)
@@ -77,7 +78,7 @@ cruft::geom::intersects (cruft::geom::segment2f ab, cruft::point2f p)
     auto const hi = max (ab.a, ab.b);
     auto const lo = min (ab.a, ab.b);
 
-    return all (p <= hi) and all (p >= lo);
+    return all (p < hi) and all (p > lo);
 }
 
 
@@ -112,6 +113,7 @@ winding (
 
 
 //-----------------------------------------------------------------------------
+// not inclusive
 template <>
 bool
 cruft::geom::intersects (
@@ -123,8 +125,10 @@ cruft::geom::intersects (
     auto const w2 = winding (s1.a, s1.b, s0.a);
     auto const w3 = winding (s1.a, s1.b, s0.b);
 
-    if (w0 != w1 and w2 != w3)
-        return true;
+    // inclusive condition. zeroes are colinear, which is fine
+    if (w0 and w1 and w2 and w3)
+        if (w0 != w1 and w2 != w3)
+            return true;
 
     if (w0 == 0 and intersects (s0, s1.a)) return true;
     if (w1 == 0 and intersects (s0, s1.b)) return true;