diff --git a/src/orange/BoundingBoxUtils.hh b/src/orange/BoundingBoxUtils.hh
index b18310fd47..0d15ed4e84 100644
--- a/src/orange/BoundingBoxUtils.hh
+++ b/src/orange/BoundingBoxUtils.hh
@@ -228,21 +228,21 @@ inline bool encloses(BoundingBox<T> const& big, BoundingBox<T> const& small)
  * intersection, the result will be inf.
  */
 template<class T, class U>
-inline CELER_FUNCTION U calc_dist_to_inside(BoundingBox<T> const& bbox,
+inline CELER_FUNCTION T calc_dist_to_inside(BoundingBox<T> const& bbox,
                                             Array<U, 3> const& pos,
                                             Array<U, 3> const& dir)
 {
     CELER_EXPECT(!is_inside(bbox, pos));
 
     // Test if an intersection is outside the bbox for a given axis
-    auto out_of_bounds = [&bbox](U intersect, int ax) {
+    auto out_of_bounds = [&bbox](T intersect, int ax) {
         return !(intersect >= bbox.lower()[ax]
                  && intersect <= bbox.upper()[ax]);
     };
 
     // Check that the intersection point occurs within the region
     // bounded by the planes of the other two axes
-    auto in_bounds = [&](int ax, U dist) {
+    auto in_bounds = [&](int ax, T dist) {
         for (auto other_ax : range(to_int(Axis::size_)))
         {
             if (other_ax == ax)
@@ -256,8 +256,8 @@ inline CELER_FUNCTION U calc_dist_to_inside(BoundingBox<T> const& bbox,
     };
 
     // Loop over all 6 planes to find the minimum intersection
-    U min_dist = numeric_limits<U>::infinity();
-    for (auto bound : range(to_int(Bound::size_)))
+    T min_dist = numeric_limits<T>::infinity();
+    for (auto bound : range(Bound::size_))
     {
         for (auto ax : range(to_int(Axis::size_)))
         {
@@ -267,10 +267,10 @@ inline CELER_FUNCTION U calc_dist_to_inside(BoundingBox<T> const& bbox,
                 continue;
             }
 
-            U dist = (bbox.point(static_cast<Bound>(bound))[ax] - pos[ax])
+            T dist = (bbox.point(static_cast<Bound>(bound))[ax] - pos[ax])
                      / dir[ax];
 
-            if (dist < 0)
+            if (dist <= 0)
             {
                 // Short circut if the plane is behind us
                 continue;
diff --git a/src/orange/detail/BIHBuilder.hh b/src/orange/detail/BIHBuilder.hh
index 87730643cb..2a5df4165d 100644
--- a/src/orange/detail/BIHBuilder.hh
+++ b/src/orange/detail/BIHBuilder.hh
@@ -36,6 +36,11 @@ namespace detail
  * node with all volumes in the stored inf_vols. This final case is useful in
  * the event that an ORANGE geometry is created via a method where volume
  * bounding boxes are not availible.
+ *
+ * Bounding boxes supplied to this builder should "bumped," i.e. expanded
+ * outward by at least floating-point epsilson from the volumes they bound.
+ * This eliminates the possiblity of accidently missing a volume during
+ * tracking.
  */
 class BIHBuilder
 {