diff --git a/examples/thread/thread.q b/examples/thread/thread.q
index 8e33e07..6d0493b 100644
--- a/examples/thread/thread.q
+++ b/examples/thread/thread.q
@@ -1,5 +1,4 @@
 import io
-import sys
 import thread
 
 main() {
@@ -12,5 +11,4 @@ main() {
 work() {
 	io.out("[ ] start\n")
 	io.out("[x] end\n")
-	sys.exit(0)
 }
\ No newline at end of file
diff --git a/lib/thread/thread_linux.q b/lib/thread/thread_linux.q
index be70f4f..5179bed 100644
--- a/lib/thread/thread_linux.q
+++ b/lib/thread/thread_linux.q
@@ -1,9 +1,22 @@
 import sys
 
+const clone {
+	vm      0x100
+	fs      0x200
+	files   0x400
+	sighand 0x800
+	parent  0x8000
+	thread  0x10000
+	io      0x80000000
+}
+
 create(func *Any) -> Int {
 	size := 4096
 	stack := sys.mmap(0, size, 0x1|0x2, 0x02|0x20|0x100|0x20000)
-	rip := stack + size - 8
-	store(rip, 8, func)
-	return sys.clone(0x100|0x200|0x400|0x800|0x8000|0x10000|0x80000000, rip)
+	stack += size
+	stack -= 8
+	store(stack, 8, _exit)
+	stack -= 8
+	store(stack, 8, func)
+	return sys.clone(clone.vm|clone.fs|clone.files|clone.sighand|clone.parent|clone.thread|clone.io, stack)
 }
\ No newline at end of file
diff --git a/src/compiler/finalize.go b/src/compiler/finalize.go
index dc21b8a..c317754 100644
--- a/src/compiler/finalize.go
+++ b/src/compiler/finalize.go
@@ -21,6 +21,7 @@ func (r *Result) finalize() {
 	}
 
 	final.Call("main.main")
+	final.Label(asm.LABEL, "_exit")
 
 	switch config.TargetOS {
 	case config.Linux:
diff --git a/src/core/ExpressionToMemory.go b/src/core/ExpressionToMemory.go
index 21f01f6..461cc1c 100644
--- a/src/core/ExpressionToMemory.go
+++ b/src/core/ExpressionToMemory.go
@@ -26,6 +26,11 @@ func (f *Function) ExpressionToMemory(node *expression.Expression, memory asm.Me
 				return types.AnyPointer, nil
 			}
 
+			if name == "_exit" {
+				f.MemoryLabel(asm.STORE, memory, "_exit")
+				return types.AnyPointer, nil
+			}
+
 			return nil, errors.New(&errors.UnknownIdentifier{Name: name}, f.File, node.Token.Position)
 		}
 
diff --git a/src/core/Fold.go b/src/core/Fold.go
index 46615de..eaaf0cd 100644
--- a/src/core/Fold.go
+++ b/src/core/Fold.go
@@ -27,6 +27,23 @@ func (f *Function) Fold(expr *expression.Expression) error {
 		return nil
 	}
 
+	if expr.Token.Kind == token.Period {
+		left := expr.Children[0]
+		leftText := left.Token.Text(f.File.Bytes)
+		right := expr.Children[1]
+		rightText := right.Token.Text(f.File.Bytes)
+		constant, isConst := f.Constants[f.Package+"."+leftText+"."+rightText]
+
+		if !isConst {
+			return nil
+		}
+
+		value, err := f.ToNumber(constant.Value)
+		expr.Value = value
+		expr.IsFolded = true
+		return err
+	}
+
 	canFold := true
 
 	for _, child := range expr.Children {