diff --git a/src/build/core/CompileCall.go b/src/build/core/CompileCall.go
index 9251510..7ac3d10 100644
--- a/src/build/core/CompileCall.go
+++ b/src/build/core/CompileCall.go
@@ -1,7 +1,7 @@
 package core
 
 import (
-	"fmt"
+	"strings"
 
 	"git.akyoto.dev/cli/q/src/build/asm"
 	"git.akyoto.dev/cli/q/src/build/errors"
@@ -30,7 +30,11 @@ func (f *Function) CompileCall(root *expression.Expression) error {
 	isSyscall := name == "syscall"
 
 	if !isSyscall {
-		fullName = fmt.Sprintf("%s.%s", pkg, name)
+		tmp := strings.Builder{}
+		tmp.WriteString(pkg)
+		tmp.WriteString(".")
+		tmp.WriteString(name)
+		fullName = tmp.String()
 		_, exists := f.Functions[fullName]
 
 		if !exists {