diff --git a/lib/uh/wm/client.rb b/lib/uh/wm/client.rb
index 328ccfa..c24b040 100644
--- a/lib/uh/wm/client.rb
+++ b/lib/uh/wm/client.rb
@@ -66,6 +66,20 @@ module Uh
         @window.focus
         self
       end
+
+      def kill
+        if @window.icccm_wm_protocols.include? :WM_DELETE_WINDOW
+          @window.icccm_wm_delete
+        else
+          @window.kill
+        end
+        self
+      end
+
+      def kill!
+        window.kill
+        self
+      end
     end
   end
 end
diff --git a/spec/support/factories.rb b/spec/support/factories.rb
index 73c32ab..3c7381a 100644
--- a/spec/support/factories.rb
+++ b/spec/support/factories.rb
@@ -17,11 +17,12 @@ module Factories
       modifier_mask:  modifier_mask
   end
 
-  def mock_window override_redirect: false
+  def mock_window override_redirect: false, icccm_wm_protocols: []
     instance_spy Uh::Window, 'window',
       to_s:               'wid',
       name:               'wname',
       wclass:             'wclass',
-      override_redirect?: override_redirect
+      override_redirect?: override_redirect,
+      icccm_wm_protocols: icccm_wm_protocols
   end
 end
diff --git a/spec/uh/wm/client_spec.rb b/spec/uh/wm/client_spec.rb
index d074646..807743c 100644
--- a/spec/uh/wm/client_spec.rb
+++ b/spec/uh/wm/client_spec.rb
@@ -1,7 +1,8 @@
 module Uh
   module WM
     RSpec.describe Client do
-      let(:window)      { mock_window }
+      let(:protocols)   { [] }
+      let(:window)      { mock_window icccm_wm_protocols: protocols }
       let(:geo)         { build_geo }
       subject(:client)  { described_class.new window, geo }
 
@@ -143,6 +144,37 @@ module Uh
           expect(client.focus).to be client
         end
       end
+
+      describe '#kill' do
+        it 'kills the window' do
+          expect(window).to receive :kill
+          client.kill
+        end
+
+        it 'returns self' do
+          expect(client.kill).to be client
+        end
+
+        context 'when window supports icccm wm delete' do
+          let(:protocols) { [:WM_DELETE_WINDOW] }
+
+          it 'icccm deletes the window' do
+            expect(window).to receive :icccm_wm_delete
+            client.kill
+          end
+        end
+      end
+
+      describe '#kill!' do
+        it 'kills the window' do
+          expect(window).to receive :kill
+          client.kill!
+        end
+
+        it 'returns self' do
+          expect(client.kill!).to be client
+        end
+      end
     end
   end
 end