diff --git a/src/ifcgeom_schema_agnostic/boolean_utils.cpp b/src/ifcgeom_schema_agnostic/boolean_utils.cpp
index b58d061a30..d6c4b144a4 100644
--- a/src/ifcgeom_schema_agnostic/boolean_utils.cpp
+++ b/src/ifcgeom_schema_agnostic/boolean_utils.cpp
@@ -683,29 +683,43 @@ bool IfcGeom::util::boolean_subtraction_2d_using_builder(const TopoDS_Shape & a_
 					BRep_Tool::Curve(e1, u21, u22)
 				);
 
-				// @todo: extend this to work in case of multiple extrema and curved segments.
-				const bool unbounded_intersects = (!ecc.Extrema().IsParallel() && ecc.NbExtrema() == 1 && ecc.Distance(1) < eps);
-				if (unbounded_intersects) {
-					ecc.Parameters(1, U1, U2);
+				if (!ecc.Extrema().IsParallel() && ecc.NbExtrema() == 1) {
+					// @todo: extend this to work in case of multiple extrema and curved segments.
+					gp_Pnt p1, p2;
+					ecc.Points(1, p1, p2);
 
-					if (u11 > u12) {
-						std::swap(u11, u12);
-					}
-					if (u21 > u22) {
-						std::swap(u21, u22);
-					}
+					// #3616 Only take into account orthogonal distance between closest points on curve
+					// to see whether inside tolerance. Current DY is hardcoded. The sensible default
+					// for walls.
+					gp_Vec vec(p1, p2);
+					Standard_Real d = vec.Dot(gp::DY());
+					gp_Vec projected = d * gp::DY();
+					gp_Vec ortho_remainder = vec - projected;
+					Standard_Real ortho_distance = ortho_remainder.Magnitude();
 
-					/// @todo: tfk: probably need different thresholds on non-linear curves
-					u11 -= eps;
-					u12 += eps;
-					u21 -= eps;
-					u22 += eps;
+					const bool unbounded_intersects = ortho_distance < eps;
+					if (unbounded_intersects) {
+						ecc.Parameters(1, U1, U2);
 
-					if (u11 < U1 && U1 < u12 && u21 < U2 && U2 < u22) {
-						// Edge curves belonging to different operands intersect, don't process
-						// using builder.
-						Logger::Notice("Intersecting boundaries");
-						return false;
+						if (u11 > u12) {
+							std::swap(u11, u12);
+						}
+						if (u21 > u22) {
+							std::swap(u21, u22);
+						}
+
+						/// @todo: tfk: probably need different thresholds on non-linear curves
+						u11 -= eps;
+						u12 += eps;
+						u21 -= eps;
+						u22 += eps;
+
+						if (u11 < U1 && U1 < u12 && u21 < U2 && U2 < u22) {
+							// Edge curves belonging to different operands intersect, don't process
+							// using builder.
+							Logger::Notice("Intersecting boundaries");
+							return false;
+						}
 					}
 				}
 			}