diff --git a/src/drc/drc/built-in-macros/_drc_layer.rb b/src/drc/drc/built-in-macros/_drc_layer.rb
index 4d22374b8..fa0735ba2 100644
--- a/src/drc/drc/built-in-macros/_drc_layer.rb
+++ b/src/drc/drc/built-in-macros/_drc_layer.rb
@@ -842,18 +842,23 @@ CODE
     # @name smoothed
     # @brief Smoothes the polygons of the region
     # @synopsis layer.smoothed(d)
+    # @synopsis layer.smoothed(d, hv_keep)
     #
     # "Smoothing" returns a simplified version of the polygons. Simplification is 
     # achieved by removing vertices unless the resulting polygon deviates by more
     # than the given distance d from the original polygon.
     #
+    # "hv_keep" is a boolean parameter which makes the smoothing function maintain
+    # horizontal or vertical edges. The default is false, meaning horizontal or
+    # vertical edges may be changed into tilted ones.
+    #
     # This method return a layer wit the modified polygons. Merged semantics applies for this
     # method (see \raw and \clean).
     
-    def smoothed(d)
+    def smoothed(d, hv_keep = false)
       @engine._context("smoothed") do
         requires_region
-        DRCLayer::new(@engine, @engine._tcmd(self.data, 0, RBA::Region, :smoothed, @engine._make_value(d)))
+        DRCLayer::new(@engine, @engine._tcmd(self.data, 0, RBA::Region, :smoothed, @engine._make_value(d), hv_keep))
       end
     end
     
diff --git a/testdata/drc/drcSimpleTests_2.drc b/testdata/drc/drcSimpleTests_2.drc
index 5582c41dd..66faa4c55 100644
--- a/testdata/drc/drcSimpleTests_2.drc
+++ b/testdata/drc/drcSimpleTests_2.drc
@@ -12,6 +12,7 @@ c1.output(3, 0)
   
 c1.rounded_corners(0.5, 0.5, 16).output(1010, 0)
 c1.smoothed(1.5).output(1011, 0)
+c1.smoothed(1.5, true).output(1012, 0)
 
 a1.texts.output(1020, 0)
 a1.texts("A*").output(1021, 0)
diff --git a/testdata/drc/drcSimpleTests_au2.gds b/testdata/drc/drcSimpleTests_au2.gds
index c85d1eebe..76c8b8afe 100644
Binary files a/testdata/drc/drcSimpleTests_au2.gds and b/testdata/drc/drcSimpleTests_au2.gds differ