diff --git a/demo/test.py b/demo/test.py
index b117674..9c4fe5f 100644
--- a/demo/test.py
+++ b/demo/test.py
@@ -1,9 +1,7 @@
-a = 1
-def b():
-    c = 20
-    print(c)
+a = 10
+def b(x): 
+    # c = "test"
+    print(x)
 
 
-b()
-print(c)
-    
\ No newline at end of file
+b(a)
\ No newline at end of file
diff --git a/src/vm/Object.zig b/src/vm/Object.zig
index 64ef102..e1ea4d7 100644
--- a/src/vm/Object.zig
+++ b/src/vm/Object.zig
@@ -210,6 +210,7 @@ pub fn format(
 
             try writer.writeAll(")");
         },
+
         else => try writer.print("TODO: Object.format '{s}'", .{@tagName(object.tag)}),
     }
 }
diff --git a/src/vm/Vm.zig b/src/vm/Vm.zig
index fa63039..57197af 100644
--- a/src/vm/Vm.zig
+++ b/src/vm/Vm.zig
@@ -189,13 +189,13 @@ fn execLoadGlobal(vm: *Vm, inst: Instruction) !void {
 fn execLoadFast(vm: *Vm, inst: Instruction) !void {
     const var_num = inst.extra;
     const obj = vm.current_co.varnames[var_num];
+    log.debug("LoadFast obj tag: {s}", .{@tagName(obj.tag)});
     try vm.stack.append(vm.allocator, obj);
 }
 
 fn execStoreName(vm: *Vm, inst: Instruction) !void {
     const name = vm.current_co.getName(inst.extra);
     const tos = vm.stack.pop();
-
     try vm.scopes.items[vm.depth].put(vm.allocator, name, tos);
 }
 
@@ -242,6 +242,11 @@ fn execCallFunction(vm: *Vm, inst: Instruction) !void {
         vm.current_co.* = func.co.*;
 
         vm.depth += 1;
+
+        // Set the args.
+        for (args, 0..) |arg, i| {
+            vm.current_co.varnames[i] = arg;
+        }
     }
 }
 
@@ -462,6 +467,8 @@ pub fn loadConst(allocator: Allocator, inst: Marshal.Result) !Object {
 fn lookUpwards(vm: *Vm, name: []const u8) ?Object {
     const scopes = vm.scopes.items;
 
+    log.debug("lookUpwards depth {}", .{vm.depth});
+
     return obj: {
         // Check the immediate scope.
         if (scopes[vm.depth].get(name)) |val| {