diff --git a/src/Ryujinx.HLE/HOS/Services/Am/AppletAE/AllSystemAppletProxiesService/LibraryAppletCreator/ILibraryAppletAccessor.cs b/src/Ryujinx.HLE/HOS/Services/Am/AppletAE/AllSystemAppletProxiesService/LibraryAppletCreator/ILibraryAppletAccessor.cs
index c7a7cdbbe..2898f6094 100644
--- a/src/Ryujinx.HLE/HOS/Services/Am/AppletAE/AllSystemAppletProxiesService/LibraryAppletCreator/ILibraryAppletAccessor.cs
+++ b/src/Ryujinx.HLE/HOS/Services/Am/AppletAE/AllSystemAppletProxiesService/LibraryAppletCreator/ILibraryAppletAccessor.cs
@@ -119,11 +119,18 @@ namespace Ryujinx.HLE.HOS.Services.Am.AppletAE.AllSystemAppletProxiesService.Lib
         }
         
         [CommandCmif(90)]
-        // ILibraryAppletAccessor:90
+        // Unknown90(ulong[4])
         public ResultCode Unknown90(ServiceCtx context)
         {
             // NOTE: This call is performed on SDK 20+ when applet is called.
-            //       Since we don't support applets for now, it's fine to stub it.
+            //       Since we don't support most applets for now, it's fine to stub it.
+            //       Throw if values are not 0 to learn more about what this function does.
+
+            if (context.RequestData.ReadUInt64() != 0 || context.RequestData.ReadUInt64() != 0 ||
+                context.RequestData.ReadUInt64() != 0 || context.RequestData.ReadUInt64() != 0)
+            {
+                throw new ArgumentException("Invalid data: values are not 0");
+            }
             
             Logger.Stub?.PrintStub(LogClass.ServiceAm);
             return ResultCode.Success;