diff --git a/web/src/dark_theme.ts b/web/src/dark_theme.ts
index 186dd2f6e6..7a8e371a5c 100644
--- a/web/src/dark_theme.ts
+++ b/web/src/dark_theme.ts
@@ -27,4 +27,10 @@ export function disable(): void {
 
 export function default_preference_checker(): void {
     $(":root").removeClass("dark-theme").addClass("color-scheme-automatic");
+
+    if (page_params.is_spectator) {
+        const ls = localstorage();
+        ls.set("spectator-theme-preference", "automatic");
+        user_settings.color_scheme = settings_config.color_scheme_values.automatic.code;
+    }
 }
diff --git a/web/src/ui_init.js b/web/src/ui_init.js
index 965864f9b9..7c270fbb9c 100644
--- a/web/src/ui_init.js
+++ b/web/src/ui_init.js
@@ -429,6 +429,8 @@ export function initialize_everything(state_data) {
             dark_theme.enable();
         } else if (preferred_theme === "light") {
             dark_theme.disable();
+        } else {
+            dark_theme.default_preference_checker();
         }
     }