diff --git a/src/ifcgeom/ConversionSettings.h b/src/ifcgeom/ConversionSettings.h
index febd789f6b..c022bfdd1c 100644
--- a/src/ifcgeom/ConversionSettings.h
+++ b/src/ifcgeom/ConversionSettings.h
@@ -361,8 +361,8 @@ namespace ifcopenshell {
 
 			struct CircleSegments : public SettingBase<CircleSegments, int> {
 				static constexpr const char* const name = "circle-segments";
-				static constexpr const char* const description = "Number of segments to approximate full circles in CGAL kernel.";
-				static constexpr int defaultvalue = 16;
+				static constexpr const char* const description = "Number of segments to approximate full circles in the CGAL kernel. When 0 (the default) the segment count is derived from mesher-linear-deflection instead, so curves stay within the deflection tolerance regardless of radius.";
+				static constexpr int defaultvalue = 0;
 			};
 
 			struct CgalSmoothAngleDegrees : public SettingBase<CgalSmoothAngleDegrees, double> {
diff --git a/src/ifcgeom/kernels/cgal/CgalKernel.cpp b/src/ifcgeom/kernels/cgal/CgalKernel.cpp
index be109dc407..f2d8a6c6b7 100644
--- a/src/ifcgeom/kernels/cgal/CgalKernel.cpp
+++ b/src/ifcgeom/kernels/cgal/CgalKernel.cpp
@@ -431,22 +431,30 @@ namespace {
 				b += 2 * M_PI;
 			}
 			const double span = std::fabs(a - b);
-			int num_segments = (int)std::ceil(span / (2 * M_PI) * settings_.get<settings::CircleSegments>().get());
-			// CircleSegments allocates segments as a fraction of the *full* circle and is
-			// radius-agnostic. A large-radius arc spanning a small angle therefore collapses
-			// to a single chord (issue #8051: curved curtain-wall mullions became straight in
-			// the CGAL kernels while OpenCascade, which meshes by deflection, kept them curved).
-			// Enforce a deflection-based floor so the chord deviation stays within the mesher's
-			// linear deflection, matching OpenCascade behaviour.
-			const double radius = conic_radius(t);
-			const double deflection = settings_.get<settings::MesherLinearDeflection>().get();
-			if (deflection > 0. && radius > deflection) {
-				const double max_segment_angle = 2.0 * std::acos(1.0 - deflection / radius);
-				if (max_segment_angle > 0.) {
-					const int num_segments_deflection = (int)std::ceil(span / max_segment_angle);
-					if (num_segments_deflection > num_segments) {
-						num_segments = num_segments_deflection;
-					}
+			// CircleSegments controls how conics (circles, ellipses, arcs) are approximated
+			// in the CGAL kernel. Two modes, one or the other:
+			//  - CircleSegments == 0 (the default): the segment count is derived from
+			//    MesherLinearDeflection, so the chord deviation stays within the mesher's
+			//    linear deflection regardless of radius. This matches the deflection based
+			//    meshing the OpenCascade kernel already does and fixes issue #8051, where
+			//    large radius arcs (curved curtain wall mullions) collapsed to straight chords
+			//    because a fixed segment count is radius agnostic.
+			//  - CircleSegments > 0: it is used directly as the number of segments for a full
+			//    circle, giving deterministic, radius independent output.
+			int num_segments;
+			const int circle_segments = settings_.get<settings::CircleSegments>().get();
+			if (circle_segments > 0) {
+				num_segments = (int)std::ceil(span / (2 * M_PI) * circle_segments);
+			} else {
+				const double radius = conic_radius(t);
+				const double deflection = settings_.get<settings::MesherLinearDeflection>().get();
+				if (deflection > 0. && radius > deflection) {
+					const double max_segment_angle = 2.0 * std::acos(1.0 - deflection / radius);
+					num_segments = (int)std::ceil(span / max_segment_angle);
+				} else {
+					// Radius within the deflection tolerance (or no deflection set): a chord per
+					// quarter turn already keeps the deviation within tolerance.
+					num_segments = (int)std::ceil(span / (M_PI / 2.));
 				}
 			}
 			if (num_segments < 1) {
diff --git a/src/ifcopenshell-python/docs/ifcconvert/usage.rst b/src/ifcopenshell-python/docs/ifcconvert/usage.rst
index 3c6846d25b..6910e7e6fe 100644
--- a/src/ifcopenshell-python/docs/ifcconvert/usage.rst
+++ b/src/ifcopenshell-python/docs/ifcconvert/usage.rst
@@ -311,8 +311,12 @@ CLI Manual
                                             output.
       --force-space-transparency arg        Overrides transparency of spaces in 
                                             geometry output.
-      --circle-segments arg (= 16)          Number of segments to approximate full 
-                                            circles in CGAL kernel.
+      --circle-segments arg (= 0)           Number of segments to approximate full
+                                            circles in the CGAL kernel. When 0 (the
+                                            default) the segment count is derived from
+                                            mesher-linear-deflection instead, so curves
+                                            stay within the deflection tolerance
+                                            regardless of radius.
       --cgal-smooth-angle-degrees arg (= -1)
                                             Angle in degrees under which adjacent 
                                             facets will have averaged vertex 
diff --git a/src/ifcopenshell-python/docs/ifcopenshell/geometry_settings.rst b/src/ifcopenshell-python/docs/ifcopenshell/geometry_settings.rst
index f73c7edc28..6862088c6c 100644
--- a/src/ifcopenshell-python/docs/ifcopenshell/geometry_settings.rst
+++ b/src/ifcopenshell-python/docs/ifcopenshell/geometry_settings.rst
@@ -228,10 +228,10 @@ circle-segments
 +------+-----------------------+---------+
 | Type | IfcConvert Option     | Default |
 +======+=======================+=========+
-| INT  | ``--circle-segments`` | 16      |
+| INT  | ``--circle-segments`` | 0       |
 +------+-----------------------+---------+
 
-Number of segments to approximate full circles in CGAL kernel.
+Number of segments to approximate full circles in the CGAL kernel. When 0 (the default) the segment count is derived from mesher-linear-deflection instead, so curves stay within the deflection tolerance regardless of radius.
 
 context-identifiers
 ^^^^^^^^^^^^^^^^^^^