diff --git a/lib/bundler/cli.rb b/lib/bundler/cli.rb
index 91c31651da..51f71af501 100644
--- a/lib/bundler/cli.rb
+++ b/lib/bundler/cli.rb
@@ -610,17 +610,8 @@ module Bundler
     end
 
     desc "doctor [OPTIONS]", "Checks the bundle for common problems"
-    long_desc <<-D
-      Doctor scans the OS dependencies of each of the gems requested in the Gemfile. If
-      missing dependencies are detected, Bundler prints them and exits status 1.
-      Otherwise, Bundler prints a success message and exits with a status of 0.
-    D
-    method_option "gemfile", type: :string, banner: "Use the specified gemfile instead of Gemfile"
-    method_option "quiet", type: :boolean, banner: "Only output warnings and errors."
-    def doctor
-      require_relative "cli/doctor"
-      Doctor.new(options).run
-    end
+    require_relative "cli/doctor"
+    subcommand("doctor", Doctor)
 
     desc "issue", "Learn how to report an issue in Bundler"
     def issue
diff --git a/lib/bundler/cli/doctor.rb b/lib/bundler/cli/doctor.rb
new file mode 100644
index 0000000000..21437fc89f
--- /dev/null
+++ b/lib/bundler/cli/doctor.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Doctor < Thor
+    default_command(:diagnose)
+
+    desc "diagnose [OPTIONS]", "Checks the bundle for common problems"
+    long_desc <<-D
+      Doctor scans the OS dependencies of each of the gems requested in the Gemfile. If
+      missing dependencies are detected, Bundler prints them and exits status 1.
+      Otherwise, Bundler prints a success message and exits with a status of 0.
+    D
+    method_option "gemfile", type: :string, banner: "Use the specified gemfile instead of Gemfile"
+    method_option "quiet", type: :boolean, banner: "Only output warnings and errors."
+    def diagnose
+      require_relative "doctor/diagnose"
+      Diagnose.new(options).run
+    end
+  end
+end
diff --git a/lib/bundler/cli/doctor/diagnose.rb b/lib/bundler/cli/doctor/diagnose.rb
index 160ad13b99..c32a1b5369 100644
--- a/lib/bundler/cli/doctor/diagnose.rb
+++ b/lib/bundler/cli/doctor/diagnose.rb
@@ -65,7 +65,7 @@ module Bundler
     end
 
     def check!
-      require_relative "check"
+      require_relative "../check"
       Bundler::CLI::Check.new({}).run
     end
 
diff --git a/lib/bundler/cli/issue.rb b/lib/bundler/cli/issue.rb
index e16c9b0e39..fbe9184d12 100644
--- a/lib/bundler/cli/issue.rb
+++ b/lib/bundler/cli/issue.rb
@@ -34,8 +34,8 @@ module Bundler
     end
 
     def doctor
-      require_relative "doctor"
-      Bundler::CLI::Doctor.new({}).run
+      require_relative "doctor/diagnose"
+      Bundler::CLI::Doctor::Diagnose.new({}).run
     end
   end
 end
diff --git a/spec/bundler/commands/doctor_spec.rb b/spec/bundler/commands/doctor_spec.rb
index 7c30d0e91b..456fb4ec78 100644
--- a/spec/bundler/commands/doctor_spec.rb
+++ b/spec/bundler/commands/doctor_spec.rb
@@ -4,6 +4,7 @@ require "find"
 require "stringio"
 require "bundler/cli"
 require "bundler/cli/doctor"
+require "bundler/cli/doctor/diagnose"
 
 RSpec.describe "bundle doctor" do
   before(:each) do
@@ -46,14 +47,14 @@ RSpec.describe "bundle doctor" do
     end
 
     it "exits with a success message if the installed gem has no C extensions" do
-      doctor = Bundler::CLI::Doctor.new({})
+      doctor = Bundler::CLI::Doctor::Diagnose.new({})
       allow(doctor).to receive(:lookup_with_fiddle).and_return(false)
       expect { doctor.run }.not_to raise_error
       expect(@stdout.string).to include("No issues")
     end
 
     it "exits with a success message if the installed gem's C extension dylib breakage is fine" do
-      doctor = Bundler::CLI::Doctor.new({})
+      doctor = Bundler::CLI::Doctor::Diagnose.new({})
       expect(doctor).to receive(:bundles_for_gem).exactly(2).times.and_return ["/path/to/myrack/myrack.bundle"]
       expect(doctor).to receive(:dylibs).exactly(2).times.and_return ["/usr/lib/libSystem.dylib"]
       allow(doctor).to receive(:lookup_with_fiddle).with("/usr/lib/libSystem.dylib").and_return(false)
@@ -62,7 +63,7 @@ RSpec.describe "bundle doctor" do
     end
 
     it "exits with a message if one of the linked libraries is missing" do
-      doctor = Bundler::CLI::Doctor.new({})
+      doctor = Bundler::CLI::Doctor::Diagnose.new({})
       expect(doctor).to receive(:bundles_for_gem).exactly(2).times.and_return ["/path/to/myrack/myrack.bundle"]
       expect(doctor).to receive(:dylibs).exactly(2).times.and_return ["/usr/local/opt/icu4c/lib/libicui18n.57.1.dylib"]
       allow(doctor).to receive(:lookup_with_fiddle).with("/usr/local/opt/icu4c/lib/libicui18n.57.1.dylib").and_return(true)
@@ -84,7 +85,7 @@ RSpec.describe "bundle doctor" do
     end
 
     it "exits with an error if home contains files that are not readable/writable" do
-      doctor = Bundler::CLI::Doctor.new({})
+      doctor = Bundler::CLI::Doctor::Diagnose.new({})
       allow(doctor).to receive(:lookup_with_fiddle).and_return(false)
       expect { doctor.run }.not_to raise_error
       expect(@stdout.string).to include(
@@ -106,7 +107,7 @@ RSpec.describe "bundle doctor" do
     end
 
     it "exits with an error if home contains files that are not readable" do
-      doctor = Bundler::CLI::Doctor.new({})
+      doctor = Bundler::CLI::Doctor::Diagnose.new({})
       allow(doctor).to receive(:lookup_with_fiddle).and_return(false)
       allow(@stat).to receive(:uid) { Process.uid }
       allow(File).to receive(:writable?).with(@unwritable_file) { false }
@@ -119,7 +120,7 @@ RSpec.describe "bundle doctor" do
     end
 
     it "exits without an error if home contains files that are not writable" do
-      doctor = Bundler::CLI::Doctor.new({})
+      doctor = Bundler::CLI::Doctor::Diagnose.new({})
       allow(doctor).to receive(:lookup_with_fiddle).and_return(false)
       allow(@stat).to receive(:uid) { Process.uid }
       allow(File).to receive(:writable?).with(@unwritable_file) { false }
@@ -137,7 +138,7 @@ RSpec.describe "bundle doctor" do
       end
 
       it "exits with an error if home contains files that are not readable/writable and are not owned by the current user" do
-        doctor = Bundler::CLI::Doctor.new({})
+        doctor = Bundler::CLI::Doctor::Diagnose.new({})
         allow(doctor).to receive(:lookup_with_fiddle).and_return(false)
         allow(File).to receive(:writable?).with(@unwritable_file) { false }
         allow(File).to receive(:readable?).with(@unwritable_file) { false }
@@ -149,7 +150,7 @@ RSpec.describe "bundle doctor" do
       end
 
       it "exits with a warning if home contains files that are read/write but not owned by current user" do
-        doctor = Bundler::CLI::Doctor.new({})
+        doctor = Bundler::CLI::Doctor::Diagnose.new({})
         allow(doctor).to receive(:lookup_with_fiddle).and_return(false)
         allow(File).to receive(:writable?).with(@unwritable_file) { true }
         allow(File).to receive(:readable?).with(@unwritable_file) { true }
@@ -164,7 +165,7 @@ RSpec.describe "bundle doctor" do
 
   context "when home contains filenames with special characters" do
     it "escape filename before command execute" do
-      doctor = Bundler::CLI::Doctor.new({})
+      doctor = Bundler::CLI::Doctor::Diagnose.new({})
       expect(doctor).to receive(:`).with("/usr/bin/otool -L \\$\\(date\\)\\ \\\"\\'\\\\.bundle").and_return("dummy string")
       doctor.dylibs_darwin('$(date) "\'\.bundle')
       expect(doctor).to receive(:`).with("/usr/bin/ldd \\$\\(date\\)\\ \\\"\\'\\\\.bundle").and_return("dummy string")