diff --git a/upstream/upstream.go b/upstream/upstream.go
index 3a5113d39..51543f4ed 100644
--- a/upstream/upstream.go
+++ b/upstream/upstream.go
@@ -218,15 +218,14 @@ func validateUpstreamURL(u *url.URL) (err error) {
 		host = h
 	}
 
-	_, err = netip.ParseAddr(host)
-	if err == nil {
-		return nil
-	}
-
 	// If it's an IPv6 address enclosed in square brackets with no port.
 	//
 	// See https://github.com/AdguardTeam/dnsproxy/issues/379.
-	_, err = netip.ParseAddr(u.Hostname())
+	if strings.HasPrefix(host, "[") && strings.HasSuffix(host, "]") {
+		_, err = netip.ParseAddr(host[1 : len(host)-1])
+	} else {
+		_, err = netip.ParseAddr(host)
+	}
 	if err == nil {
 		return nil
 	}