diff --git a/gerbolyze/__init__.py b/gerbolyze/__init__.py
index e817471..2989169 100755
--- a/gerbolyze/__init__.py
+++ b/gerbolyze/__init__.py
@@ -335,30 +335,6 @@ def parse_subtract_script(script, default_dilation=0.1, default_script=DEFAULT_S
         subtract_script[out_layer] = subtract_script.get(out_layer, []) + [(in_layer, dilation)]
     return subtract_script
 
-# Parameter parsing foo
-#======================
-
-def parse_bbox(bbox):
-    if not bbox:
-        return None
-    elems = [ int(elem) for elem in re.split('[,/ ]', bbox) ]
-    if len(elems) not in (2, 4):
-        raise click.BadParameter(
-                '--bbox must be either two floating-point values like: w,h or four like: x,y,w,h')
-
-    elems = [ float(e) for e in elems ]
-
-    if len(elems) == 2:
-        bounds = [0, 0, *elems]
-    else:
-        bounds = elems
-    
-    # now transform bounds to the format pcb-tools uses. Instead of (x, y, w, h) or even (x1, y1, x2, y2), that
-    # is ((x1, x2), (y1, y2)
-
-    x, y, w, h = bounds
-    return ((x, x+w), (y, y+h))
-
 # Utility foo
 # ===========
 
diff --git a/gerbolyze/tests/resources/layers.svg b/gerbolyze/tests/resources/layers.svg
index fd263c7..1879033 100644
--- a/gerbolyze/tests/resources/layers.svg
+++ b/gerbolyze/tests/resources/layers.svg
@@ -94,7 +94,7 @@
      inkscape:document-units="mm"
      showgrid="false"
      inkscape:zoom="1.326224"
-     inkscape:cx="153.44316"
+     inkscape:cx="145.52594"
      inkscape:cy="302.3622"
      inkscape:window-width="1920"
      inkscape:window-height="1011"
@@ -109,38 +109,38 @@
        aria-label="Top Paste"
        transform="matrix(0.70241335,0,0,0.70241335,-8.580134,-12.02921)"
        id="text1132"
-       style="font-style:italic;font-size:9.00953px;font-family:'Bodoni Moda';-inkscape-font-specification:'Bodoni Moda Italic';text-align:justify;white-space:pre;shape-inside:url(#rect1134);display:inline;opacity:1;stroke:#000000;stroke-width:0.141882;stroke-linecap:round;stroke-linejoin:round">
+       style="font-style:italic;font-size:9.00953px;font-family:'Bodoni Moda';-inkscape-font-specification:'Bodoni Moda Italic';text-align:justify;white-space:pre;shape-inside:url(#rect1134);display:inline;opacity:1;stroke:#000000;stroke-width:0.14236632;stroke-linecap:round;stroke-linejoin:round;stroke-dasharray:none">
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+         style="stroke-width:0.14236632;stroke-linejoin:round;stroke-dasharray:none"
          id="path7617" />
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+         style="stroke-width:0.14236632;stroke-linejoin:round;stroke-dasharray:none"
          id="path7631" />
     </g>
   </g>
@@ -544,7 +544,7 @@
          id="path7795" />
     </g>
     <rect
-       style="fill:none;stroke:#000000;stroke-width:0.0999999;stroke-linecap:round;stroke-dasharray:none"
+       style="fill:none;stroke:#000000;stroke-width:0.09;stroke-linecap:round;stroke-dasharray:none"
        id="rect5087"
        width="79.900002"
        height="159.89999"
diff --git a/gerbolyze/tests/test_integration.py b/gerbolyze/tests/test_integration.py
index 668e745..7456e85 100644
--- a/gerbolyze/tests/test_integration.py
+++ b/gerbolyze/tests/test_integration.py
@@ -20,6 +20,7 @@ import subprocess
 import tempfile
 from pathlib import Path
 
+import gerbonara
 import pytest
 
 
@@ -67,7 +68,20 @@ def test_convert_layers():
     infile = reference_path('layers.svg')
     with tempfile.TemporaryDirectory() as out_dir:
         run_command('python3', '-m', 'gerbolyze', 'convert', infile, out_dir)
-        out_dir = Path(out_dir)
-        print(list(out_dir.glob('*')))
-        assert False
+        stack = gerbonara.layers.LayerStack.open(out_dir)
+        for layer, dia in {
+                'top paste':        0.100,
+                'top silk':         0.110,
+                'top mask':         0.120,
+                'top copper':       0.130,
+                'bottom copper':    0.140,
+                'bottom mask':      0.150,
+                'bottom silk':      0.160,
+                'bottom paste':     0.170,
+                'mechanical outline':    0.09}.items():
+            assert set(round(ap.diameter, 4) for ap in stack[layer].apertures) == {dia, 0.05}
+
+        # Note: svg-flatten rounds these diameters to the geometric tolerance given on the command line (0.01mm by
+        # default). Thus, these values are different from the more precise values in the SVG.
+        assert set(stack.drill_layers[0].drill_sizes()) == {0.67, 0.51}
 
diff --git a/svg-flatten/src/svg_doc.cpp b/svg-flatten/src/svg_doc.cpp
index 47e73ee..77b561e 100644
--- a/svg-flatten/src/svg_doc.cpp
+++ b/svg-flatten/src/svg_doc.cpp
@@ -282,7 +282,7 @@ void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml
             }
 
             double area = nopencv::polygon_area(geom_poly);
-            double polsby_popper = 4*M_PI * area / pow(nopencv::polygon_perimeter(geom_poly), 2);
+            double polsby_popper = 4*std::numbers::pi * area / pow(nopencv::polygon_perimeter(geom_poly), 2);
             polsby_popper = fabs(fabs(polsby_popper) - 1.0);
             if (polsby_popper < ctx.settings().drill_test_polsby_popper_tolerance) {
                 if (!ctx.clip().empty()) {
@@ -298,7 +298,9 @@ void gerbolyze::SVGDocument::export_svg_path(RenderContext &ctx, const pugi::xml
                 d2p centroid = nopencv::polygon_centroid(geom_poly);
                 centroid[0] /= clipper_scale;
                 centroid[1] /= clipper_scale;
-                double diameter = sqrt(4*fabs(area)/M_PI) / clipper_scale;
+                /* area of n-gon with circumradius 1 relative to circle with radius 1 */
+                double ngon_area_relative = p.size()/(2*std::numbers::pi) * sin(2*std::numbers::pi / p.size());
+                double diameter = sqrt(4*fabs(area)/std::numbers::pi) / clipper_scale / ngon_area_relative;
                 double tolerance = ctx.settings().geometric_tolerance_mm / 2;
                 diameter = round(diameter/tolerance) * tolerance;
                 ctx.sink() << ApertureToken(diameter) << FlashToken(centroid);