diff --git a/lib/irb/extend-command.rb b/lib/irb/extend-command.rb
index 9fa2ce5d86..d0829a06c4 100644
--- a/lib/irb/extend-command.rb
+++ b/lib/irb/extend-command.rb
@@ -162,6 +162,7 @@ module IRB # :nodoc:
 
       [
         :irb_help, :Help, "cmd/help",
+        [:show_doc, NO_OVERRIDE],
         [:help, NO_OVERRIDE],
       ],
 
diff --git a/test/irb/test_cmd.rb b/test/irb/test_cmd.rb
index 31cd786ffe..d4b952490d 100644
--- a/test/irb/test_cmd.rb
+++ b/test/irb/test_cmd.rb
@@ -376,16 +376,18 @@ module TestIRB
       assert_match(/Please specify the file name./, out)
     end
 
-    def test_help
-      out, _ = execute_lines(
-        "help 'String#gsub'\n",
-        "\n",
-      )
+    def test_help_and_show_doc
+      ["help", "show_doc"].each do |cmd|
+        out, _ = execute_lines(
+          "#{cmd} 'String#gsub'\n",
+          "\n",
+        )
 
-      # the former is what we'd get without document content installed, like on CI
-      # the latter is what we may get locally
-      possible_rdoc_output = [/Nothing known about String#gsub/, /Returns a copy of self with all occurrences of the given pattern/]
-      assert(possible_rdoc_output.any? { |output| output.match?(out) }, "Expect the help command to match one of the possible outputs")
+        # the former is what we'd get without document content installed, like on CI
+        # the latter is what we may get locally
+        possible_rdoc_output = [/Nothing known about String#gsub/, /Returns a copy of self with all occurrences of the given pattern/]
+        assert(possible_rdoc_output.any? { |output| output.match?(out) }, "Expect the `#{cmd}` command to match one of the possible outputs")
+      end
     ensure
       # this is the only way to reset the redefined method without coupling the test with its implementation
       EnvUtil.suppress_warning { load "irb/cmd/help.rb" }