diff --git a/README.md b/README.md
index c6756f5..09d464e 100644
--- a/README.md
+++ b/README.md
@@ -357,6 +357,19 @@ cd /root/of/this/repo
 conda activate ./env
 ```
 
+### How to release
+
+1. Checkout branch 
+2. Update version X.Y.Z.YYYYMMDD in `pyproject.toml`
+    - Bump X.Y.Z according to semantic versioning 2.0.0
+    - Set YYYYMMDD according to current UTC date
+4. Update `poetry.lock` with `poetry update`
+5. Push changes
+6. Merge with main
+7. Create release with title and tag `vX.Y.Z.YYYYMMDD` (prepend `v` in both)
+8. PyPI is automatically published
+
+
 ### Paradigms
 
 #### Use the top-level `__init__.py` to declare a 'public' API for the module
diff --git a/jsonschema_fill_default/jsonschema_fill_default.py b/jsonschema_fill_default/jsonschema_fill_default.py
index c6534ba..debabd0 100644
--- a/jsonschema_fill_default/jsonschema_fill_default.py
+++ b/jsonschema_fill_default/jsonschema_fill_default.py
@@ -136,8 +136,9 @@ def _fill_properties(instance: dict, schema: dict):
             if _property not in instance:
                 instance[_property] = dict()
             fill_default(instance[_property], subschema)
-            if len(instance[_property]) == 0:  # No default found inside
-                del instance[_property]
+            if isinstance(instance[_property], (list, tuple, dict, set)):
+                if len(instance[_property]) == 0:  # No default found inside
+                    del instance[_property]
         if _property not in instance \
                 and "default" in subschema:
             instance[_property] = subschema["default"]
diff --git a/pyproject.toml b/pyproject.toml
index 56e6b78..2bb8afe 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "jsonschema-fill-default"
-version = "0.1.1.20250130"
+version = "0.1.2.20250130"
 description = "Fill a JSON instance with the missing defaults from its JSON Schema Draft 2020-12-valid schema"
 authors = ["Lars Maxfield"]
 readme = "README.md"
diff --git a/tests/unit/test_validate_and_fill.py b/tests/unit/test_validate_and_fill.py
index 03ac64f..06e004e 100644
--- a/tests/unit/test_validate_and_fill.py
+++ b/tests/unit/test_validate_and_fill.py
@@ -703,7 +703,7 @@
                 }
             }
         ]
-    },
+    }
 }