diff --git a/src/gerbonara/cad/kicad/footprints.py b/src/gerbonara/cad/kicad/footprints.py
index ee156c4..487ce1e 100644
--- a/src/gerbonara/cad/kicad/footprints.py
+++ b/src/gerbonara/cad/kicad/footprints.py
@@ -885,11 +885,14 @@ class Footprint:
                 (self.zones if zones else []),
                 self.groups if groups else [])
 
-    def render(self, layer_stack, layer_map, x=0, y=0, rotation=0, text=False, flip=False, variables={}, cache=None):
+    def render(self, layer_stack, layer_map=None, x=0, y=0, rotation=0, text=False, flip=False, variables={}, cache=None):
         x += self.at.x
         y += self.at.y
         rotation += math.radians(self.at.rotation)
 
+        if layer_map is None:
+            layer_map = {kc_id: gn_id for kc_id, gn_id in LAYER_MAP_K2G.items() if gn_id in layer_stack}
+
         for obj in self.objects(pads=False, text=text, zones=False, groups=False):
             if not (layer := layer_map.get(obj.layer)):
                 continue
@@ -946,8 +949,7 @@ class Footprint:
     def bounding_box(self, unit=MM):
         if not hasattr(self, '_bounding_box'):
             stack = LayerStack()
-            layer_map = {kc_id: gn_id for kc_id, gn_id in LAYER_MAP_K2G.items() if gn_id in stack}
-            self.render(stack, layer_map, x=0, y=0, rotation=0, flip=False, text=False, variables={})
+            self.render(stack, layer_map=None, x=0, y=0, rotation=0, flip=False, text=False, variables={})
             self._bounding_box = stack.bounding_box(unit)
         return self._bounding_box
 
@@ -972,9 +974,7 @@ class FootprintInstance(Positioned):
         if self.value is not None:
             variables['VALUE'] = str(self.value)
 
-        layer_map = {kc_id: gn_id for kc_id, gn_id in LAYER_MAP_K2G.items() if gn_id in layer_stack}
-
-        self.sexp.render(layer_stack, layer_map,
+        self.sexp.render(layer_stack, layer_map=None,
                          x=x, y=y, rotation=rotation,
                          flip=flip,
                          text=(not self.hide_text),
diff --git a/src/gerbonara/layers.py b/src/gerbonara/layers.py
index 96c2230..3491eef 100644
--- a/src/gerbonara/layers.py
+++ b/src/gerbonara/layers.py
@@ -738,10 +738,7 @@ class LayerStack:
 
         :param prefix: Store output files under the given prefix inside the zip file
         """
-        if path.is_file():
-            if overwrite_existing:
-                path.unlink()
-            else:
+        if path.is_file() and not overwrite_existing:
                 raise ValueError('output zip file already exists and overwrite_existing is False')
 
         if gerber_settings and not excellon_settings: