diff --git a/tls.go b/tls.go
index 8eef884..e11e7dd 100644
--- a/tls.go
+++ b/tls.go
@@ -102,7 +102,7 @@ func DialWithDialer(dialer *net.Dialer, network, addr string, config *Config) (*
 	timeout := dialer.Timeout
 
 	if !dialer.Deadline.IsZero() {
-		deadlineTimeout := dialer.Deadline.Sub(time.Now())
+		deadlineTimeout := time.Until(dialer.Deadline)
 		if timeout == 0 || deadlineTimeout < timeout {
 			timeout = deadlineTimeout
 		}