diff --git a/lib/pleroma/web/api_spec/operations/account_operation.ex b/lib/pleroma/web/api_spec/operations/account_operation.ex
index a64762285..4111d1613 100644
--- a/lib/pleroma/web/api_spec/operations/account_operation.ex
+++ b/lib/pleroma/web/api_spec/operations/account_operation.ex
@@ -545,10 +545,18 @@ defp create_request do
           description: "Invite token required when the registrations aren't public"
         },
         birthday: %Schema{
-          type: :string,
           nullable: true,
           description: "User's birthday",
-          format: :date
+          anyOf: [
+            %Schema{
+              type: :string,
+              format: :date
+            },
+            %Schema{
+              type: :string,
+              maxLength: 0
+            }
+          ]
         },
         language: %Schema{
           type: :string,
@@ -733,10 +741,18 @@ defp update_credentials_request do
         },
         actor_type: ActorType,
         birthday: %Schema{
-          type: :string,
           nullable: true,
           description: "User's birthday",
-          format: :date
+          anyOf: [
+            %Schema{
+              type: :string,
+              format: :date
+            },
+            %Schema{
+              type: :string,
+              maxLength: 0
+            }
+          ]
         },
         show_birthday: %Schema{
           allOf: [BooleanLike],
diff --git a/test/pleroma/web/mastodon_api/update_credentials_test.exs b/test/pleroma/web/mastodon_api/update_credentials_test.exs
index c2e4debc8..f5211a60e 100644
--- a/test/pleroma/web/mastodon_api/update_credentials_test.exs
+++ b/test/pleroma/web/mastodon_api/update_credentials_test.exs
@@ -390,6 +390,20 @@ test "updates the user's show_birthday status", %{conn: conn} do
       assert user_data["source"]["pleroma"]["show_birthday"] == true
     end
 
+    test "unsets birth date", %{conn: conn} do
+      patch(conn, "/api/v1/accounts/update_credentials", %{
+        "birthday" => "2001-02-12"
+      })
+
+      res =
+        patch(conn, "/api/v1/accounts/update_credentials", %{
+          "birthday" => ""
+        })
+
+      assert user_data = json_response_and_validate_schema(res, 200)
+      assert user_data["pleroma"]["birthday"] == nil
+    end
+
     test "emojis in fields labels", %{conn: conn} do
       fields = [
         %{"name" => ":firefox:", "value" => "is best 2hu"},