diff --git a/lib/nostr/event_kind.rb b/lib/nostr/event_kind.rb
index ceed11a..fabc17c 100644
--- a/lib/nostr/event_kind.rb
+++ b/lib/nostr/event_kind.rb
@@ -40,5 +40,17 @@ module Nostr
     # @return [Integer]
     #
     ENCRYPTED_DIRECT_MESSAGE = 4
+
+    # A special event with kind 9374. See NIP-57.
+    #
+    # @return [Integer]
+    #
+    ZAP_REQUEST = 9734
+
+    # A special event with kind 9375. See NIP-57.
+    #
+    # @return [Integer]
+    #
+    ZAP_RECEIPT = 9735
   end
 end
diff --git a/spec/nostr/event_kind_spec.rb b/spec/nostr/event_kind_spec.rb
index 7aa36e6..7210c3a 100644
--- a/spec/nostr/event_kind_spec.rb
+++ b/spec/nostr/event_kind_spec.rb
@@ -32,4 +32,16 @@ RSpec.describe Nostr::EventKind do
       expect(described_class::ENCRYPTED_DIRECT_MESSAGE).to eq(4)
     end
   end
+
+  describe '::ZAP_REQUEST' do
+    it 'is an integer' do
+      expect(described_class::ZAP_REQUEST).to eq(9734)
+    end
+  end
+
+  describe '::ZAP_RECEIPT' do
+    it 'is an integer' do
+      expect(described_class::ZAP_RECEIPT).to eq(9735)
+    end
+  end
 end