diff --git a/masque/file/dxf.py b/masque/file/dxf.py
index 0d6006e..0f6dd32 100644
--- a/masque/file/dxf.py
+++ b/masque/file/dxf.py
@@ -376,5 +376,5 @@ def _mlayer2dxf(layer: layer_t) -> str:
     if isinstance(layer, int):
         return str(layer)
     if isinstance(layer, tuple):
-        return f'{layer[0]}.{layer[1]}'
+        return f'{layer[0]:d}.{layer[1]:d}'
     raise PatternError(f'Unknown layer type: {layer} ({type(layer)})')