diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0db4b22..3748109 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- Made micropip.freeze correctly list dependencies of manually installed packages.
+  [#79](https://github.com/pyodide/micropip/pull/79)
+
 ## [0.4.0] - 2023/07/25
 
 ### Added
diff --git a/micropip/_utils.py b/micropip/_utils.py
index b42a751..ea89987 100644
--- a/micropip/_utils.py
+++ b/micropip/_utils.py
@@ -187,7 +187,7 @@ def platform_to_version(platform: str) -> str:
     raise ValueError(f"Wheel interpreter version '{tag.interpreter}' is not supported.")
 
 
-def fix_package_dependencies(package_name, *, extras=None):
+def fix_package_dependencies(package_name: str, *, extras: list[str] = None) -> None:
     """Check and fix the list of dependencies for this package
 
     If you have manually installed a package and dependencies from wheels,
@@ -234,7 +234,7 @@ def fix_package_dependencies(package_name, *, extras=None):
     if extras is None:
         extras = [None]
     else:
-        extras.append(None)
+        extras = extras + [None]
     for r in package_requires:
         req = Requirement(r)
         req_extras = req.extras