diff --git a/config/initializers/doorkeeper.rb b/config/initializers/doorkeeper.rb
index a5c9caa4a..7784bec62 100644
--- a/config/initializers/doorkeeper.rb
+++ b/config/initializers/doorkeeper.rb
@@ -8,8 +8,20 @@ Doorkeeper.configure do
   end
 
   resource_owner_from_credentials do |_routes|
-    user = User.find_by(email: request.params[:username])
-    user if !user&.otp_required_for_login? && user&.valid_password?(request.params[:password])
+    if Devise.ldap_authentication
+      user = User.authenticate_with_ldap({ :email => request.params[:username], :password => request.params[:password] })
+    end
+
+    if Devise.pam_authentication
+      user ||= User.authenticate_with_ldap({ :email => request.params[:username], :password => request.params[:password] })
+    end
+
+    if user.nil?
+      user = User.find_by(email: request.params[:username])
+      user = nil unless user.valid_password?(request.params[:password])
+    end
+
+    user if !user&.otp_required_for_login?
   end
 
   # If you want to restrict access to the web interface for adding oauth authorized applications, you need to declare the block below.