diff --git a/bg_helpers.cpp b/bg_helpers.cpp
index e66ef6ac5..5a66e7d75 100644
--- a/bg_helpers.cpp
+++ b/bg_helpers.cpp
@@ -9,26 +9,20 @@
 #include "bg_operators.hpp"
 #include "bg_helpers.hpp"
 
-namespace bg_helpers {
-
-// The below implementations of buffer are similar to bg::buffer but
-// always convert to floating-point before doing work, if needed, and
-// convert back afterward, if needed.  Also, they work if expand_by is
-// 0, unlike bg::buffer.
-const int points_per_circle = 32;
-
-multi_polygon_type_fp buffer(multi_polygon_type_fp const & geometry_in, coordinate_type_fp expand_by) {
-  if (expand_by == 0 || geometry_in.size() == 0) {
-    return geometry_in;
-  }
 #ifdef GEOS_VERSION
+template <typename T>
+std::unique_ptr<geos::geom::Geometry> to_geos(const T& mp) {
   geos::io::WKTReader reader;
   std::stringstream ss;
-  ss << bg::wkt(geometry_in);
-  auto geos_in = reader.read(ss.str());
-  std::unique_ptr<geos::geom::Geometry> geos_out(geos::operation::buffer::BufferOp::bufferOp(geos_in.get(), expand_by, points_per_circle/4));
+  ss << bg::wkt(mp);
+  return reader.read(ss.str());
+}
+
+multi_polygon_type_fp from_geos(const std::unique_ptr<geos::geom::Geometry>& g) {
   geos::io::WKTWriter writer;
-  auto geos_wkt = writer.write(geos_out.get());
+  std::string geos_wkt = writer.write(g.get());
+  boost::replace_all(geos_wkt, "EMPTY, ", "");
+  boost::replace_all(geos_wkt, ", EMPTY", "");
   multi_polygon_type_fp ret;
   if (strncmp(geos_wkt.c_str(), "MULTIPOLYGON", 12) == 0) {
     bg::read_wkt(geos_wkt, ret);
@@ -38,6 +32,26 @@ multi_polygon_type_fp buffer(multi_polygon_type_fp const & geometry_in, coordina
     ret.push_back(poly);
   }
   return ret;
+}
+#endif //GEOS_VERSION
+
+namespace bg_helpers {
+
+// The below implementations of buffer are similar to bg::buffer but
+// always convert to floating-point before doing work, if needed, and
+// convert back afterward, if needed.  Also, they work if expand_by is
+// 0, unlike bg::buffer.
+const int points_per_circle = 32;
+
+multi_polygon_type_fp buffer(multi_polygon_type_fp const & geometry_in, coordinate_type_fp expand_by) {
+  if (expand_by == 0 || geometry_in.size() == 0) {
+    return geometry_in;
+  }
+#ifdef GEOS_VERSION
+  auto geos_in = to_geos(geometry_in);
+  return from_geos(
+      std::unique_ptr<geos::geom::Geometry>(
+          geos::operation::buffer::BufferOp::bufferOp(geos_in.get(), expand_by, points_per_circle/4)));
 #else
   multi_polygon_type_fp geometry_out;
   bg::buffer(geometry_in, geometry_out,
@@ -83,22 +97,10 @@ multi_polygon_type_fp buffer(linestring_type_fp const & geometry_in, CoordinateT
     return {};
   }
 #ifdef GEOS_VERSION
-  geos::io::WKTReader reader;
-  std::stringstream ss;
-  ss << bg::wkt(geometry_in);
-  auto geos_in = reader.read(ss.str());
-  std::unique_ptr<geos::geom::Geometry> geos_out(geos::operation::buffer::BufferOp::bufferOp(geos_in.get(), expand_by, points_per_circle/4));
-  geos::io::WKTWriter writer;
-  auto geos_wkt = writer.write(geos_out.get());
-  multi_polygon_type_fp ret;
-  if (strncmp(geos_wkt.c_str(), "MULTIPOLYGON", 12) == 0) {
-    bg::read_wkt(geos_wkt, ret);
-  } else {
-    polygon_type_fp poly;
-    bg::read_wkt(geos_wkt, poly);
-    ret.push_back(poly);
-  }
-  return ret;
+  auto geos_in = to_geos(geometry_in);
+  return from_geos(
+      std::unique_ptr<geos::geom::Geometry>(
+          geos::operation::buffer::BufferOp::bufferOp(geos_in.get(), expand_by, points_per_circle/4)));
 #else
   multi_polygon_type_fp geometry_out;
   bg::buffer(geometry_in, geometry_out,
@@ -120,22 +122,10 @@ multi_polygon_type_fp buffer(multi_linestring_type_fp const & geometry_in, Coord
   // multilinestring to non-intersecting paths seems to help.
   multi_linestring_type_fp mls = eulerian_paths::make_eulerian_paths(geometry_in, true, true);
 #ifdef GEOS_VERSION
-  geos::io::WKTReader reader;
-  std::stringstream ss;
-  ss << bg::wkt(mls);
-  auto geos_in = reader.read(ss.str());
-  std::unique_ptr<geos::geom::Geometry> geos_out(geos::operation::buffer::BufferOp::bufferOp(geos_in.get(), expand_by, points_per_circle/4));
-  geos::io::WKTWriter writer;
-  auto geos_wkt = writer.write(geos_out.get());
-  multi_polygon_type_fp ret;
-  if (strncmp(geos_wkt.c_str(), "MULTIPOLYGON", 12) == 0) {
-    bg::read_wkt(geos_wkt, ret);
-  } else {
-    polygon_type_fp poly;
-    bg::read_wkt(geos_wkt, poly);
-    ret.push_back(poly);
-  }
-  return ret;
+  auto geos_in = to_geos(mls);
+  return from_geos(
+      std::unique_ptr<geos::geom::Geometry>(
+          geos::operation::buffer::BufferOp::bufferOp(geos_in.get(), expand_by, points_per_circle/4)));
 #else
   if (expand_by == 0) {
     return {};
diff --git a/bg_helpers.hpp b/bg_helpers.hpp
index f01b5350c..89308eea6 100644
--- a/bg_helpers.hpp
+++ b/bg_helpers.hpp
@@ -6,10 +6,8 @@
 #ifdef GEOS_VERSION
 #include <geos/io/WKTReader.h>
 #include <geos/io/WKTWriter.h>
-#include <geos/operation/buffer/BufferOp.h>
 #endif // GEOS_VERSION
 
-
 namespace bg_helpers {
 
 // The below implementations of buffer are similar to bg::buffer but
diff --git a/drill.cpp b/drill.cpp
index 6036bb40a..09761dc1d 100644
--- a/drill.cpp
+++ b/drill.cpp
@@ -471,7 +471,7 @@ bool ExcellonProcessor::millhole(std::ofstream &of, double start_x, double start
         double zdiff_line1 = 0;
         double zdiff_hcircle2 = 0;
         // Distance traveled by one half circle
-        double dist_hcircle = M_PI * millr;
+        double dist_hcircle = boost::math::constants::pi<double>() * millr;
         if (slot) {
           // How much to step down per pass
           double zstep = cutter->zwork / stepcount;