diff --git a/lib/alchemy/admin/preview_url.rb b/lib/alchemy/admin/preview_url.rb
index 3bcde8a71e..1e3abcb146 100644
--- a/lib/alchemy/admin/preview_url.rb
+++ b/lib/alchemy/admin/preview_url.rb
@@ -45,8 +45,10 @@ def url_for(page)
         if @preview_config && uri
           uri_class.build(
             host: uri.host,
+            port: uri.port,
             path: page.url_path,
             userinfo: userinfo,
+            query: { alchemy_preview_mode: true }.to_param,
           ).to_s
         else
           routes.admin_page_path(page)
diff --git a/spec/libraries/admin/preview_url_spec.rb b/spec/libraries/admin/preview_url_spec.rb
index 8c2b9e91f7..24fa0c2cb4 100644
--- a/spec/libraries/admin/preview_url_spec.rb
+++ b/spec/libraries/admin/preview_url_spec.rb
@@ -39,7 +39,7 @@
         end
 
         it "returns the configured preview url" do
-          is_expected.to eq "http://www.example.com/#{page.urlname}"
+          is_expected.to eq "http://www.example.com/#{page.urlname}?alchemy_preview_mode=true"
         end
       end
 
@@ -51,7 +51,7 @@
         end
 
         it "returns the configured preview url with https" do
-          is_expected.to eq "https://www.example.com/#{page.urlname}"
+          is_expected.to eq "https://www.example.com/#{page.urlname}?alchemy_preview_mode=true"
         end
       end
 
@@ -67,7 +67,19 @@
         end
 
         it "returns the configured preview url with userinfo" do
-          is_expected.to eq "https://foo:baz@www.example.com/#{page.urlname}"
+          is_expected.to eq "https://foo:baz@www.example.com/#{page.urlname}?alchemy_preview_mode=true"
+        end
+      end
+
+      context "with a port configured" do
+        before do
+          stub_alchemy_config(:preview, {
+            "host" => "https://www.example.com:8080",
+          })
+        end
+
+        it "returns the configured preview url with userinfo" do
+          is_expected.to eq "https://www.example.com:8080/#{page.urlname}?alchemy_preview_mode=true"
         end
       end
 
@@ -86,7 +98,7 @@
           end
 
           it "returns the configured preview url for that site" do
-            is_expected.to eq "http://new.example.com/#{page.urlname}"
+            is_expected.to eq "http://new.example.com/#{page.urlname}?alchemy_preview_mode=true"
           end
         end
 
@@ -102,7 +114,7 @@
             end
 
             it "returns the default configured preview url" do
-              is_expected.to eq "http://www.example.com/#{page.urlname}"
+              is_expected.to eq "http://www.example.com/#{page.urlname}?alchemy_preview_mode=true"
             end
           end
 
@@ -132,7 +144,7 @@
         end
 
         it "returns the preview url without urlname" do
-          is_expected.to eq "https://www.example.com/"
+          is_expected.to eq "https://www.example.com/?alchemy_preview_mode=true"
         end
       end
     end