diff --git a/src/__private__/__line_intersection.scad b/src/__private__/__line_intersection.scad
index 9d958107..a72cfb44 100644
--- a/src/__private__/__line_intersection.scad
+++ b/src/__private__/__line_intersection.scad
@@ -1,4 +1,4 @@
-function __line_intersection(line_pts1, line_pts2) = 
+function __line_intersection(line_pts1, line_pts2, epsilon = 0.0001) = 
     let(
         a1 = line_pts1[0],
         a2 = line_pts1[1],
@@ -8,5 +8,5 @@ function __line_intersection(line_pts1, line_pts2) =
         b = b2 - b1, 
         s = b1 - a1
     )
-    cross(a, b) == 0 ? [] :  // they are parallel or conincident edges
+    abs(cross(a, b)) == epsilon ? [] :  // they are parallel or conincident edges
         a1 + a * cross(s, b) / cross(a, b);
\ No newline at end of file
diff --git a/src/bijection_offset.scad b/src/bijection_offset.scad
index 838c574b..d02291e7 100644
--- a/src/bijection_offset.scad
+++ b/src/bijection_offset.scad
@@ -42,12 +42,12 @@ function _bijection__bijection_offset_edges(edges, d) =
         _bijection_offset_edge(edge, dx, dy)
     ];
 
-function bijection_offset(pts, d) = 
+function bijection_offset(pts, d, epsilon = 0.0001) = 
     let(
         es = __lines_from(pts, true), 
         offset_es = _bijection__bijection_offset_edges(es, d),
         leng = len(offset_es),
-        last_p = __line_intersection(offset_es[leng - 1], offset_es[0])
+        last_p = __line_intersection(offset_es[leng - 1], offset_es[0], epsilon)
     )
     concat(
         [
@@ -55,7 +55,7 @@ function bijection_offset(pts, d) =
             let(
                 this_edge = offset_es[i],
                 next_edge = offset_es[i + 1],
-                p = __line_intersection(this_edge, next_edge)
+                p = __line_intersection(this_edge, next_edge, epsilon)
             )
             // p == p to avoid [nan, nan], because [nan, nan] != [nan, nan]
             if(p != [] && p == p) p
diff --git a/src/trim_shape.scad b/src/trim_shape.scad
index 3980f7b6..5c849dee 100644
--- a/src/trim_shape.scad
+++ b/src/trim_shape.scad
@@ -4,7 +4,7 @@ include <__private__/__lines_from.scad>;
 
 function _trim_shape_any_intersection_sub(lines, line, lines_leng, i, epsilon) =
     let(
-        p = __line_intersection(lines[i], line)
+        p = __line_intersection(lines[i], line, epsilon)
     )
     (p != [] && __in_line(line, p, epsilon) && __in_line(lines[i], p, epsilon)) ? [i, p] : _trim_shape_any_intersection(lines, line, lines_leng, i + 1, epsilon);