diff --git a/r2/r2/lib/validator/preferences.py b/r2/r2/lib/validator/preferences.py
index c7252dbdb..e86f7e9c7 100644
--- a/r2/r2/lib/validator/preferences.py
+++ b/r2/r2/lib/validator/preferences.py
@@ -83,8 +83,10 @@ PREFS_VALIDATORS = dict(
     pref_use_global_defaults=VBoolean("use_global_defaults"),
     pref_creddit_autorenew=VBoolean("creddit_autorenew"),
     pref_enable_default_themes=VBoolean("enable_default_themes", False),
-    pref_default_theme_sr=VSRByName("theme_selector", False),
-    pref_other_theme=VSRByName("other_theme", False),
+    pref_default_theme_sr=VSRByName("theme_selector", required=False,
+        return_srname=True),
+    pref_other_theme=VSRByName("other_theme", required=False,
+        return_srname=True),
     pref_beta=VBoolean('beta'),
     pref_legacy_search=VBoolean('legacy_search'),
     pref_threaded_modmail=VBoolean('threaded_modmail', False),
@@ -140,8 +142,9 @@ def filter_prefs(prefs, user):
         prefs['pref_highlight_new_comments'] = True
 
     # check stylesheet override
-    if feature.is_enabled('stylesheets_everywhere', user=user):
-        override_sr = prefs['pref_default_theme_sr']
+    if (feature.is_enabled('stylesheets_everywhere', user=user) and
+            prefs['pref_default_theme_sr']):
+        override_sr = Subreddit._by_name(prefs['pref_default_theme_sr'])
         if not override_sr:
             del prefs['pref_default_theme_sr']
             if prefs['pref_enable_default_themes']:
diff --git a/r2/r2/lib/validator/validator.py b/r2/r2/lib/validator/validator.py
index c3297c0ac..2e9299ed9 100644
--- a/r2/r2/lib/validator/validator.py
+++ b/r2/r2/lib/validator/validator.py
@@ -720,8 +720,9 @@ class VAvailableSubredditName(VSubredditName):
 
 
 class VSRByName(Validator):
-    def __init__(self, sr_name, required=True):
+    def __init__(self, sr_name, required=True, return_srname=False):
         self.required = required
+        self.return_srname = return_srname
         Validator.__init__(self, sr_name)
 
     def run(self, sr_name):
@@ -732,7 +733,10 @@ class VSRByName(Validator):
             sr_name = sr_path_rx.sub('\g<name>', sr_name.strip())
             try:
                 sr = Subreddit._by_name(sr_name)
-                return sr
+                if self.return_srname:
+                    return sr.name
+                else:
+                    return sr
             except NotFound:
                 self.set_error(errors.SUBREDDIT_NOEXIST, code=400)