diff --git a/cl/_testdata/importpkg/in.go b/cl/_testdata/importpkg/in.go
index f9c1c830..96afbd51 100644
--- a/cl/_testdata/importpkg/in.go
+++ b/cl/_testdata/importpkg/in.go
@@ -5,5 +5,6 @@ import "github.com/goplus/llgo/cl/internal/stdio"
 var hello = [...]int8{'H', 'e', 'l', 'l', 'o', '\n', 0}
 
 func main() {
+	_ = stdio.Max(2, 100)
 	stdio.Printf(&hello[0])
 }
diff --git a/cl/_testdata/importpkg/out.ll b/cl/_testdata/importpkg/out.ll
index c07ae22b..de2212b5 100644
--- a/cl/_testdata/importpkg/out.ll
+++ b/cl/_testdata/importpkg/out.ll
@@ -28,10 +28,13 @@ _llgo_2:                                          ; preds = %_llgo_1, %_llgo_0
 define void @main() {
 _llgo_0:
   call void @main.init()
+  %0 = call i64 @"github.com/goplus/llgo/cl/internal/stdio.Max"(i64 2, i64 100)
   call void (ptr, ...) @printf(ptr @main.hello)
   ret void
 }
 
 declare void @"github.com/goplus/llgo/cl/internal/stdio.init"()
 
+declare i64 @"github.com/goplus/llgo/cl/internal/stdio.Max"(i64, i64)
+
 declare void @printf(ptr, ...)
diff --git a/cl/internal/stdio/printf.go b/cl/internal/stdio/printf.go
index 38fffa6f..ac080937 100644
--- a/cl/internal/stdio/printf.go
+++ b/cl/internal/stdio/printf.go
@@ -8,3 +8,10 @@ const (
 
 //go:linkname Printf printf
 func Printf(format *int8, __llgo_va_list ...any)
+
+func Max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
diff --git a/internal/build/build_install.go b/internal/build/build_install.go
index 166fcaf8..84075441 100644
--- a/internal/build/build_install.go
+++ b/internal/build/build_install.go
@@ -48,7 +48,7 @@ const (
 )
 
 func Do(args []string, mode Mode) {
-	flags, patterns := parseArgs(args)
+	flags, patterns, verbose := parseArgs(args)
 	cfg := &packages.Config{
 		Mode:       loadSyntax | packages.NeedExportFile,
 		BuildFlags: flags,
@@ -67,8 +67,10 @@ func Do(args []string, mode Mode) {
 	}
 
 	llssa.Initialize(llssa.InitAll)
-	// llssa.SetDebug(llssa.DbgFlagAll)
-	// cl.SetDebug(cl.DbgFlagAll)
+	if verbose {
+		llssa.SetDebug(llssa.DbgFlagAll)
+		cl.SetDebug(cl.DbgFlagAll)
+	}
 
 	prog := llssa.NewProgram(nil)
 	llFiles := make([]string, 0, len(pkgs))
@@ -122,13 +124,18 @@ func allPkgs(initial []*packages.Package, mode ssa.BuilderMode) (prog *ssa.Progr
 	return
 }
 
-func parseArgs(args []string) (flags, patterns []string) {
+func parseArgs(args []string) (flags, patterns []string, verbose bool) {
 	for i, arg := range args {
 		if !strings.HasPrefix(arg, "-") {
-			return args[:i], args[i:]
+			flags, patterns = args[:i], args[i:]
+			return
+		}
+		if arg == "-v" {
+			verbose = true
 		}
 	}
-	return args, nil
+	flags = args
+	return
 }
 
 func check(err error) {