diff --git a/test/geom/aabb.cpp b/test/geom/aabb.cpp
index 177d0553..23571147 100644
--- a/test/geom/aabb.cpp
+++ b/test/geom/aabb.cpp
@@ -1,15 +1,45 @@
 #include "geom/aabb.hpp"
+#include "geom/ray.hpp"
 
 #include "tap.hpp"
 
 #include <tuple>
 
-using util::geom::aabb2f;
-
 
 int
 main (int, char**)
 {
     util::TAP::logger tap;
+
+    {
+
+
+        static struct {
+            util::point2f lo;
+            util::point2f hi;
+
+            util::point2f base;
+            util::vector2f direction;
+
+            float distance;
+
+            const char *message;
+        } const TESTS[] {
+            {
+                { 1, 1 }, { 9, 9 },
+                { 2, 2 }, { 1/std::sqrt (2.f), 1/std::sqrt (2.f) },
+                std::sqrt (7.f * 7 * 2),
+                "ray doesn't give negative distance to closest edge"
+            }
+        };
+
+        for (auto const &t: TESTS) {
+            util::geom::aabb2f const shape (t.lo, t.hi);
+            util::geom::ray2f const r {t.base, t.direction};
+            tap.expect_eq (distance (r, shape), t.distance, "%!", t.message);
+        }
+    };
+
+
     return tap.status ();
 }