--- bison/internal/versions.bzl
+++ bison/internal/versions.bzl
@@ -17,6 +17,7 @@
 """Supported versions of GNU Bison."""
 
 _MIRRORS = [
+    "https://ftpmirror.gnu.org/bison/",
     "https://mirrors.kernel.org/gnu/bison/",
     "https://ftp.gnu.org/gnu/bison/",
 ]