diff --git a/config/initializers/omniauth.rb b/config/initializers/omniauth.rb
index 2f4b4f6b..0edb9b67 100644
--- a/config/initializers/omniauth.rb
+++ b/config/initializers/omniauth.rb
@@ -46,12 +46,14 @@ Rails.application.config.middleware.use OmniAuth::Builder do
         scope: %w(profile email),
         access_type: 'online',
         name: 'google',
+        redirect_uri: ENV['OAUTH2_REDIRECT'].presence || nil,
         setup: SETUP_PROC
     end
     if Rails.configuration.omniauth_office365
       Rails.application.config.providers << :office365
 
       provider :office365, ENV['OFFICE365_KEY'], ENV['OFFICE365_SECRET'],
+      redirect_uri: ENV['OAUTH2_REDIRECT'].presence || nil,
       setup: SETUP_PROC
     end
   end
diff --git a/sample.env b/sample.env
index ca870e80..6e6496fc 100644
--- a/sample.env
+++ b/sample.env
@@ -44,6 +44,10 @@ OFFICE365_KEY=
 OFFICE365_SECRET=
 OFFICE365_HD=
 
+# OAUTH2_REDIRECT allows you to specify the redirect_url passed to oauth on sign in.
+# It is useful for cases when Greenlight is deployed behind a Network Load Balancer or proxy
+OAUTH2_REDIRECT=
+
 # LDAP Login Provider (optional)
 #
 # You can enable LDAP authentication by providing values for the variables below.