diff --git a/Plugin/clAuiBook.cpp b/Plugin/clAuiBook.cpp
index 73771568da..078626a484 100644
--- a/Plugin/clAuiBook.cpp
+++ b/Plugin/clAuiBook.cpp
@@ -153,15 +153,21 @@ class clAuiBookArt : public wxAuiDefaultTabArt
 
             wxPoint bottom_right = tab_rect.GetBottomRight();
             wxPoint top_right = tab_rect.GetTopRight();
-            bottom_right.y += 1;
-            bottom_right.x += 1;
-            top_right.x += 1;
-
             wxPoint bottom_left = tab_rect.GetBottomLeft();
             wxPoint top_left = tab_rect.GetTopLeft();
+
+#ifndef __WXMSW__
             bottom_left.y += 1;
+            bottom_right.y += 1;
+            bottom_right.x += 1;
+            top_right.x += 1;
             bottom_left.x -= 1;
             top_left.x -= 1;
+#endif
+
+#ifdef __WXMSW__
+            dcref.DrawLine(top_right, top_left);
+#endif
 
             dcref.DrawLine(top_left, bottom_left);
             dcref.DrawLine(top_right, bottom_right);