diff --git a/libs/kimath/include/geometry/shape_poly_set.h b/libs/kimath/include/geometry/shape_poly_set.h
index 962be5fb91..4ec8d82de8 100644
--- a/libs/kimath/include/geometry/shape_poly_set.h
+++ b/libs/kimath/include/geometry/shape_poly_set.h
@@ -1012,7 +1012,7 @@ public:
                   CORNER_STRATEGY aCornerStrategy = ROUND_ALL_CORNERS );
 
     void Deflate( int aAmount, int aCircleSegmentsCount,
-                  CORNER_STRATEGY aCornerStrategy = ROUND_ALL_CORNERS )
+                  CORNER_STRATEGY aCornerStrategy = CHAMFER_ALL_CORNERS )
     {
         Inflate( -aAmount, aCircleSegmentsCount, aCornerStrategy );
     }
diff --git a/pcbnew/zone_filler.cpp b/pcbnew/zone_filler.cpp
index 9d33c7befe..b521f6b640 100644
--- a/pcbnew/zone_filler.cpp
+++ b/pcbnew/zone_filler.cpp
@@ -1524,7 +1524,7 @@ bool ZONE_FILLER::fillCopperZone( const ZONE* aZone, PCB_LAYER_ID aLayer, PCB_LA
      */
 
     if( half_min_width - epsilon > epsilon )
-        aFillPolys.Deflate( half_min_width - epsilon, numSegs, cornerStrategy );
+        aFillPolys.Deflate( half_min_width - epsilon, numSegs, fastCornerStrategy );
 
     // Min-thickness is the web thickness.  On the other hand, a blob min-thickness by
     // min-thickness is not useful.  Since there's no obvious definition of web vs. blob, we