diff --git a/pyarn/lockfile.py b/pyarn/lockfile.py
index b936d78..64ba261 100644
--- a/pyarn/lockfile.py
+++ b/pyarn/lockfile.py
@@ -19,7 +19,7 @@
 import logging
 import re
 from pathlib import Path
-from typing import Optional, Pattern
+from typing import Any, Dict, Optional, Pattern
 
 from ply import lex, yacc
 
@@ -36,15 +36,15 @@
 class Package:
     def __init__(
         self,
-        name,
-        version,
-        url=None,
-        checksum=None,
-        path=None,
-        relpath=None,
-        dependencies=None,
-        alias=None,
-    ):
+        name: str,
+        version: str,
+        url: Optional[str] = None,
+        checksum: Optional[str] = None,
+        path: Optional[str] = None,
+        relpath: Optional[str] = None,
+        dependencies: Optional[Dict[str, str]] = None,
+        alias: Optional[str] = None,
+    ) -> None:
         if not name:
             raise ValueError("Package name was not provided")
 
@@ -68,7 +68,7 @@ def relpath(self, path: Optional[str]) -> None:
         self.path = path
 
     @classmethod
-    def from_dict(cls, raw_name, data):
+    def from_dict(cls, raw_name: str, data: Dict[str, Any]) -> "Package":
         name_at_version = re.compile(r"(?P<name>@?[^@]+)(?:@(?P<version>[^,]*))?")
 
         # _version is the version as declared in package.json, not the resolved version
@@ -83,9 +83,14 @@ def from_dict(cls, raw_name, data):
         if _version:
             path = cls.get_path_from_version_specifier(_version)
 
+        # Ensure the resolved version key exists to appease mypy
+        version = data.get("version")
+        if not version:
+            raise ValueError("Package version was not provided")
+
         return cls(
             name=name,
-            version=data.get("version"),
+            version=version,
             url=data.get("resolved"),
             checksum=data.get("integrity"),
             path=path,
diff --git a/tests/test_lockfile.py b/tests/test_lockfile.py
index 9efc9f5..6393f75 100644
--- a/tests/test_lockfile.py
+++ b/tests/test_lockfile.py
@@ -123,16 +123,21 @@ def test_packages():
     assert packages[0].path is None
 
 
-def test_packages_no_version():
+def test_lock_packages_no_version():
     data = "breakfast@^1.1.1:\n  eggs bacon"
     lock = lockfile.Lockfile.from_str(data)
     with pytest.raises(ValueError, match="Package version was not provided"):
         lock.packages()
 
 
+def test_package_no_version():
+    with pytest.raises(ValueError, match="Package version was not provided"):
+        lockfile.Package("breakfast", None)  # type: ignore[arg-type]
+
+
 def test_packages_no_name():
     with pytest.raises(ValueError, match="Package name was not provided"):
-        lockfile.Package(None, "1.0.0")
+        lockfile.Package(None, "1.0.0")  # type: ignore[arg-type]
 
 
 def test_packages_url():