diff --git a/caddyhttp/httpserver/mitm.go b/caddyhttp/httpserver/mitm.go
index 5d9f0d170..e5360205b 100644
--- a/caddyhttp/httpserver/mitm.go
+++ b/caddyhttp/httpserver/mitm.go
@@ -7,6 +7,7 @@ import (
 	"io"
 	"net"
 	"net/http"
+	"strconv"
 	"strings"
 	"sync"
 )