diff --git a/PluralKit.API/Controllers/v2/SwitchControllerV2.cs b/PluralKit.API/Controllers/v2/SwitchControllerV2.cs
index 6623edbc..fe79760e 100644
--- a/PluralKit.API/Controllers/v2/SwitchControllerV2.cs
+++ b/PluralKit.API/Controllers/v2/SwitchControllerV2.cs
@@ -163,11 +163,13 @@ namespace PluralKit.API
             if (!Guid.TryParse(switchRef, out var switchId))
                 throw APIErrors.InvalidSwitchId;
 
-            var value = data.Value<Instant>("timestamp");
-            if (value == null)
+            var valueStr = data.Value<string>("timestamp").NullIfEmpty();
+            if (valueStr == null)
                 // todo
                 throw APIErrors.GenericBadRequest;
 
+            var value = Instant.FromDateTimeOffset(DateTime.Parse(valueStr).ToUniversalTime());
+
             var system = await ResolveSystem("@me");
             if (system == null)
                 throw APIErrors.SystemNotFound;
diff --git a/PluralKit.API/Startup.cs b/PluralKit.API/Startup.cs
index 04e6b434..c21b5a64 100644
--- a/PluralKit.API/Startup.cs
+++ b/PluralKit.API/Startup.cs
@@ -140,7 +140,10 @@ namespace PluralKit.API
                 var exc = ctx.Features.Get<IExceptionHandlerPathFeature>();
 
                 // handle common ISEs that are generated by invalid user input
-                if (exc.Error is InvalidCastException && exc.Error.Message.Contains("Newtonsoft.Json"))
+                if (
+                       (exc.Error is InvalidCastException && exc.Error.Message.Contains("Newtonsoft.Json"))
+                    || (exc.Error is FormatException && exc.Error.Message.Contains("was not recognized as a valid DateTime"))
+                )
                 {
                     ctx.Response.StatusCode = 400;
                     await ctx.Response.WriteAsync("{\"message\":\"400: Bad Request\",\"code\":0}");