diff --git a/PluralKit.Bot/Commands/SystemFront.cs b/PluralKit.Bot/Commands/SystemFront.cs
index 330a9f77..7b8021c8 100644
--- a/PluralKit.Bot/Commands/SystemFront.cs
+++ b/PluralKit.Bot/Commands/SystemFront.cs
@@ -104,7 +104,7 @@ public class SystemFront
         );
     }
 
-    public async Task FrontPercent(Context ctx, PKSystem? system = null, string durationStr = "30d", bool ignoreNoFronters = false, bool showFlat = false, PKGroup? group = null)
+    public async Task FrontPercent(Context ctx, PKSystem? system, string? durationStr, bool ignoreNoFronters = false, bool showFlat = false, PKGroup? group = null)
     {
         if (system == null && group == null) throw Errors.NoSystemError(ctx.DefaultPrefix);
         if (system == null) system = await GetGroupSystem(ctx, group);
@@ -114,6 +114,9 @@ public class SystemFront
         var totalSwitches = await ctx.Repository.GetSwitchCount(system.Id);
         if (totalSwitches == 0) throw Errors.NoRegisteredSwitches;
 
+        if (durationStr == null)
+            durationStr = "30d";
+
         // Picked the UNIX epoch as a random date
         // even though we don't store switch timestamps in UNIX time
         // I assume most people won't have switches logged previously to that (?)