diff --git a/pyproject.toml b/pyproject.toml
index a59ed6d..8da313f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -44,5 +44,16 @@ dev = [
     "mpl_fontkit"
 ]
 
+[tool.flit.sdist]
+exclude = [
+    "docs",
+    "app",
+    "data",
+    "img",
+    "tests",
+    "scripts",
+    "readthedocs.yaml",
+]
+
 [tool.ruff.lint.per-file-ignores]
 "__init__.py" = ["F401"]
\ No newline at end of file
diff --git a/src/marsilea/__init__.py b/src/marsilea/__init__.py
index c9492a8..ec6df4e 100644
--- a/src/marsilea/__init__.py
+++ b/src/marsilea/__init__.py
@@ -1,6 +1,6 @@
 """Declarative creation of composable visualization"""
 
-__version__ = "0.3.6"
+__version__ = "0.4.0"
 
 import marsilea.plotter as plotter
 from ._deform import Deformation
diff --git a/src/marsilea/base.py b/src/marsilea/base.py
index 3e7f481..fd8b786 100644
--- a/src/marsilea/base.py
+++ b/src/marsilea/base.py
@@ -73,8 +73,9 @@ def custom_legend(self, legend_func, name=None):
         Parameters
         ----------
 
-        legend_func : Callable that return `Artist <matplotlib.artist.Artists>`
-            A function that return the legend object
+        legend_func : Callable
+            A function that return the legend object,
+            the legend must be an `Artist <matplotlib.artist.Artists>`
         name : str, optional
             The name of the legend