diff --git a/common/geometry/shape_arc.cpp b/common/geometry/shape_arc.cpp
index a3b7959a08..3c22a8c23f 100644
--- a/common/geometry/shape_arc.cpp
+++ b/common/geometry/shape_arc.cpp
@@ -259,7 +259,7 @@ const SHAPE_LINE_CHAIN SHAPE_ARC::ConvertToPolyline( double aAccuracy ) const
         double a = sa;
 
         if( n != 0 )
-            sa += m_centralAngle * (double) i / (double) n;
+            a = m_centralAngle * (double) i / (double) n;
 
         double x = c.x + r * cos( a * M_PI / 180.0 );
         double y = c.y + r * sin( a * M_PI / 180.0 );