diff --git a/common/lib/dependabot/config/file.rb b/common/lib/dependabot/config/file.rb
index 6dd9c2512d..4a58691541 100644
--- a/common/lib/dependabot/config/file.rb
+++ b/common/lib/dependabot/config/file.rb
@@ -1,4 +1,4 @@
-# typed: true
+# typed: strict
 # frozen_string_literal: true
 
 require "dependabot/config/update_config"
@@ -10,11 +10,22 @@ module Config
     class File
       extend T::Sig
 
-      attr_reader :updates, :registries
+      sig { returns(T::Array[T::Hash[Symbol, String]]) }
+      attr_reader :updates
 
+      sig { returns T::Array[T.untyped] }
+      attr_reader :registries
+
+      sig do
+        params(
+          updates: T.nilable(T::Array[T::Hash[Symbol, String]]),
+          registries: T.nilable(T::Array[T.untyped])
+        )
+          .void
+      end
       def initialize(updates:, registries: nil)
-        @updates = updates || []
-        @registries = registries || []
+        @updates = T.let(updates || [], T::Array[T::Hash[Symbol, String]])
+        @registries = T.let(registries || [], T::Array[T.untyped])
       end
 
       sig do