diff --git a/core/data.rbs b/core/data.rbs
index 24edc27f0..d23fd92df 100644
--- a/core/data.rbs
+++ b/core/data.rbs
@@ -367,6 +367,7 @@ class Data
   #     #=> true
   #
   def to_h: () -> Hash[Symbol, untyped]
+          | [K, V] () { (Symbol key, untyped value) -> [K, V] } -> Hash[K, V]
 
   # <!-- rdoc-file=struct.c -->
   # Returns a string representation of `self`:
diff --git a/test/stdlib/Data_test.rb b/test/stdlib/Data_test.rb
index e25241f05..fe4219240 100644
--- a/test/stdlib/Data_test.rb
+++ b/test/stdlib/Data_test.rb
@@ -40,4 +40,17 @@ def test_with
       data, :with, email: "test@example.com"
     )
   end
+
+  def test_to_h
+    data = D.new("soutaro@example.com", "soutaro")
+
+    assert_send_type(
+      "() -> Hash[Symbol, untyped]",
+      data, :to_h
+    )
+    assert_send_type(
+      "() { (Symbol, untyped) -> [String, String] } -> Hash[String, String]",
+      data, :to_h, &-> (key, value) { [key.to_s, value.to_s] }
+    )
+  end
 end