diff --git a/features/steps/output_steps.rb b/features/steps/output_steps.rb
index 558dd10..14f53a2 100644
--- a/features/steps/output_steps.rb
+++ b/features/steps/output_steps.rb
@@ -22,6 +22,7 @@ Usage: uhwm [options]
 options:
     -h, --help                       print this message
     -v, --version                    enable verbose mode
+    -d, --debug                      enable debug mode
   eoh
 end
 
diff --git a/lib/uh/wm/cli.rb b/lib/uh/wm/cli.rb
index 4330cc1..6bb70bf 100644
--- a/lib/uh/wm/cli.rb
+++ b/lib/uh/wm/cli.rb
@@ -53,6 +53,11 @@ module Uh
             @env.verbose = true
             @env.log_logger_level
           end
+
+          opts.on '-d', '--debug', 'enable debug mode' do
+            @env.debug = true
+            @env.log_logger_level
+          end
         end
       end
     end
diff --git a/spec/uh/wm/cli_spec.rb b/spec/uh/wm/cli_spec.rb
index d901983..4fd9f7f 100644
--- a/spec/uh/wm/cli_spec.rb
+++ b/spec/uh/wm/cli_spec.rb
@@ -102,6 +102,20 @@ module Uh
           end
         end
 
+        context 'with debug option' do
+          let(:arguments) { %w[-d] }
+
+          it 'sets the env as debug' do
+            cli.parse_arguments!
+            expect(cli.env).to be_debug
+          end
+
+          it 'tells the env to log its logger level' do
+            expect(cli.env).to receive :log_logger_level
+            cli.parse_arguments!
+          end
+        end
+
         context 'with invalid option' do
           let(:arguments) { %w[--unknown-option] }