diff --git a/Underanalyzer/Decompiler/AST/Nodes/VariableCallNode.cs b/Underanalyzer/Decompiler/AST/Nodes/VariableCallNode.cs
index e0da287..6b8d4f7 100644
--- a/Underanalyzer/Decompiler/AST/Nodes/VariableCallNode.cs
+++ b/Underanalyzer/Decompiler/AST/Nodes/VariableCallNode.cs
@@ -75,7 +75,7 @@ public void Print(ASTPrinter printer)
             {
                 // We have a "builtin" type on our variable, so use what's on the stack instead.
                 // Have to also check if we *need* "self." or not, if that's what Instance happens to be.
-                if (Instance is not InstanceTypeNode instType2 || instType2.InstanceType != IGMInstruction.InstanceType.Self ||
+                if (Instance is not InstanceTypeNode instType2 || instType2.InstanceType != IGMInstruction.InstanceType.Self || // TODO: for later investigation: does Builtin also need to be checked in 2024 versions?
                     printer.LocalVariableNames.Contains(variable.Variable.Name.Content) ||
                     printer.TopFragmentContext.NamedArguments.Contains(variable.Variable.Name.Content))
                 {
diff --git a/Underanalyzer/Decompiler/AST/Nodes/VariableNode.cs b/Underanalyzer/Decompiler/AST/Nodes/VariableNode.cs
index 8bd13b4..4cee4de 100644
--- a/Underanalyzer/Decompiler/AST/Nodes/VariableNode.cs
+++ b/Underanalyzer/Decompiler/AST/Nodes/VariableNode.cs
@@ -244,6 +244,7 @@ public void Print(ASTPrinter printer)
                 switch (value)
                 {
                     case (int)InstanceType.Self:
+                    case (int)InstanceType.Builtin:
                         if (printer.LocalVariableNames.Contains(Variable.Name.Content) ||
                             printer.TopFragmentContext.NamedArguments.Contains(Variable.Name.Content))
                         {
diff --git a/UnderanalyzerTest/DecompileContext.DecompileToString.cs b/UnderanalyzerTest/DecompileContext.DecompileToString.cs
index c3e4e68..8e8cc30 100644
--- a/UnderanalyzerTest/DecompileContext.DecompileToString.cs
+++ b/UnderanalyzerTest/DecompileContext.DecompileToString.cs
@@ -1820,4 +1820,48 @@ function default_args_locals(arg0 = 123)
             """
         );
     }
+
+    [Fact]
+    public void TestArgumentsSelf()
+    {
+        TestUtil.VerifyDecompileResult(
+            """
+            :[0]
+            b [4]
+
+            > gml_Script_default_arg_color (locals=0, args=1)
+            :[1]
+            push.v arg.argument0
+            pushbltn.v builtin.undefined
+            cmp.v.v EQ
+            bf [3]
+
+            :[2]
+            push.i 1
+            pop.v.i arg.argument0
+
+            :[3]
+            pushi.e 123
+            pop.v.i builtin.arg0
+            exit.i
+
+            :[4]
+            push.i [function]gml_Script_default_arg_color
+            conv.i.v
+            pushi.e -1
+            conv.i.v
+            call.i method 2
+            dup.v 0
+            pushi.e -1
+            pop.v.v [stacktop]self.default_arg_color
+            popz.v
+            """,
+            """
+            function default_arg_color(arg0 = 1)
+            {
+                self.arg0 = 123;
+            }
+            """
+        );
+    }
 }