diff --git a/vlib/builtin/int.v b/vlib/builtin/int.v
index 24a98c54c5..686a1c6806 100644
--- a/vlib/builtin/int.v
+++ b/vlib/builtin/int.v
@@ -125,8 +125,8 @@ pub fn (b bool) str() string {
 pub fn (n int) hex() string {
 	s := n.str()
 	hex := malloc(s.len + 3) // 0x + \n 
-	C.sprintf(hex, '0x%x', n)
-	return tos(hex, s.len + 3)
+	count := int(C.sprintf(hex, '0x%x', n))
+	return tos(hex, count)
 }
 
 pub fn (n i64) hex() string {