diff --git a/osu.Game/Configuration/RealmRulesetSetting.cs b/osu.Game/Configuration/RealmRulesetSetting.cs
index c88a261ad2..d1e1bb9ea2 100644
--- a/osu.Game/Configuration/RealmRulesetSetting.cs
+++ b/osu.Game/Configuration/RealmRulesetSetting.cs
@@ -5,6 +5,8 @@ using System;
 using osu.Game.Database;
 using Realms;
 
+#nullable enable
+
 namespace osu.Game.Configuration
 {
     [MapTo(@"RulesetSetting")]
@@ -16,12 +18,13 @@ namespace osu.Game.Configuration
         [Indexed]
         public int RulesetID { get; set; }
 
-        public int? Variant { get; set; }
+        [Indexed]
+        public int Variant { get; set; }
 
-        public string Key { get; set; }
+        public string Key { get; set; } = string.Empty;
 
         [MapTo(nameof(Value))]
-        public string ValueString { get; set; }
+        public string ValueString { get; set; } = string.Empty;
 
         public object Value
         {
diff --git a/osu.Game/OsuGameBase.cs b/osu.Game/OsuGameBase.cs
index 36406ded08..46614ca0ad 100644
--- a/osu.Game/OsuGameBase.cs
+++ b/osu.Game/OsuGameBase.cs
@@ -465,7 +465,7 @@ namespace osu.Game
                             ValueString = dkb.StringValue,
                             Key = dkb.Key,
                             RulesetID = dkb.RulesetID.Value,
-                            Variant = dkb.Variant
+                            Variant = dkb.Variant ?? 0,
                         });
                     }
                 }
diff --git a/osu.Game/Rulesets/Configuration/RulesetConfigManager.cs b/osu.Game/Rulesets/Configuration/RulesetConfigManager.cs
index a97976392a..f4b4e2978c 100644
--- a/osu.Game/Rulesets/Configuration/RulesetConfigManager.cs
+++ b/osu.Game/Rulesets/Configuration/RulesetConfigManager.cs
@@ -16,7 +16,7 @@ namespace osu.Game.Rulesets.Configuration
     {
         private readonly RealmContextFactory realmFactory;
 
-        private readonly int? variant;
+        private readonly int variant;
 
         private List<RealmRulesetSetting> databasedSettings = new List<RealmRulesetSetting>();
 
@@ -31,7 +31,7 @@ namespace osu.Game.Rulesets.Configuration
 
             rulesetId = ruleset.ID ?? -1;
 
-            this.variant = variant;
+            this.variant = variant ?? 0;
 
             Load();