diff --git a/CmlLib/Core/Launcher/MLaunch.cs b/CmlLib/Core/Launcher/MLaunch.cs
index 9ee0ab8..09f0693 100644
--- a/CmlLib/Core/Launcher/MLaunch.cs
+++ b/CmlLib/Core/Launcher/MLaunch.cs
@@ -111,19 +111,21 @@ public string[] CreateArg()
             // version-specific jvm arguments
             if (version.JvmArguments != null)
                 args.AddRange(Mapper.MapInterpolation(version.JvmArguments, argDict));
-            
+
             // default jvm arguments
             if (launchOption.JVMArguments != null)
                 args.AddRange(launchOption.JVMArguments);
+
             else
+                args.AddRange(DefaultJavaParameter);
+
+            if (!args.Where(arg => arg.StartsWith("-Xm")).Any())
             {
                 if (launchOption.MaximumRamMb > 0)
                     args.Add("-Xmx" + launchOption.MaximumRamMb + "m");
 
                 if (launchOption.MinimumRamMb > 0)
                     args.Add("-Xms" + launchOption.MinimumRamMb + "m");
-                
-                args.AddRange(DefaultJavaParameter);
             }
 
             if (version.JvmArguments == null)