diff --git a/app/assets/javascripts/discourse/models/login-method.js.es6 b/app/assets/javascripts/discourse/models/login-method.js.es6
index 6fab5b0577..5105179104 100644
--- a/app/assets/javascripts/discourse/models/login-method.js.es6
+++ b/app/assets/javascripts/discourse/models/login-method.js.es6
@@ -127,7 +127,11 @@ export function findAll(siteSettings, capabilities, isMobileDevice) {
         params.displayPopup = true;
       }
 
-      if (["facebook", "google_oauth2", "twitter", "yahoo"].includes(name)) {
+      if (
+        ["facebook", "google_oauth2", "twitter", "yahoo", "github"].includes(
+          name
+        )
+      ) {
         params.canConnect = true;
       }
 
diff --git a/lib/auth/github_authenticator.rb b/lib/auth/github_authenticator.rb
index e5ac4ee30e..aaf43fa1b2 100644
--- a/lib/auth/github_authenticator.rb
+++ b/lib/auth/github_authenticator.rb
@@ -15,6 +15,17 @@ class Auth::GithubAuthenticator < Auth::Authenticator
     info&.screen_name || ""
   end
 
+  def can_revoke?
+    true
+  end
+
+  def revoke(user, skip_remote: false)
+    info = GithubUserInfo.find_by(user_id: user.id)
+    raise Discourse::NotFound if info.nil?
+    info.destroy!
+    true
+  end
+
   class GithubEmailChecker
     include ::HasErrors
 
@@ -30,7 +41,7 @@ class Auth::GithubAuthenticator < Auth::Authenticator
 
   end
 
-  def after_authenticate(auth_token)
+  def after_authenticate(auth_token, existing_account: nil)
     result = Auth::Result.new
 
     data = auth_token[:info]
@@ -46,6 +57,15 @@ class Auth::GithubAuthenticator < Auth::Authenticator
 
     user_info = GithubUserInfo.find_by(github_user_id: github_user_id)
 
+    if existing_account && (user_info.nil? || existing_account.id != user_info.user_id)
+      user_info.destroy! if user_info
+      user_info = GithubUserInfo.create(
+        user_id: existing_account.id,
+        screen_name: screen_name,
+        github_user_id: github_user_id
+        )
+    end
+
     if user_info
       # If there's existing user info with the given GitHub ID, that's all we
       # need to know.
diff --git a/spec/components/auth/github_authenticator_spec.rb b/spec/components/auth/github_authenticator_spec.rb
index 17fff987cd..4ade566557 100644
--- a/spec/components/auth/github_authenticator_spec.rb
+++ b/spec/components/auth/github_authenticator_spec.rb
@@ -202,6 +202,36 @@ describe Auth::GithubAuthenticator do
       expect(result.email_valid).to eq(true)
     end
 
+    it 'can connect to a different existing user account' do
+      user1 = Fabricate(:user)
+      user2 = Fabricate(:user)
+
+      GithubUserInfo.create!(user_id: user1.id, github_user_id: 100, screen_name: "boris")
+
+      result = authenticator.after_authenticate(data, existing_account: user2)
+
+      expect(result.user.id).to eq(user2.id)
+      expect(GithubUserInfo.exists?(user_id: user1.id)).to eq(false)
+      expect(GithubUserInfo.exists?(user_id: user2.id)).to eq(true)
+    end
+
+  end
+
+  context 'revoke' do
+    let(:user) { Fabricate(:user) }
+    let(:authenticator) { Auth::GithubAuthenticator.new }
+
+    it 'raises exception if no entry for user' do
+      expect { authenticator.revoke(user) }.to raise_error(Discourse::NotFound)
+    end
+
+      it 'revokes correctly' do
+        GithubUserInfo.create!(user_id: user.id, github_user_id: 100, screen_name: "boris")
+        expect(authenticator.can_revoke?).to eq(true)
+        expect(authenticator.revoke(user)).to eq(true)
+        expect(authenticator.description_for_user(user)).to eq("")
+      end
+
   end
 
   describe 'avatar retrieval' do