diff --git a/config.sh b/config.sh
index 77393a8..c0865ba 100644
--- a/config.sh
+++ b/config.sh
@@ -19,10 +19,6 @@ function pre_build {
         # See https://github.com/matplotlib/matplotlib/issues/10649
         export LDFLAGS="-headerpad_max_install_names"
         build_new_zlib
-        local default_backend=macosx
-    else
-        # Tk not available by default on manylinux build container.
-        local default_backend=TkAgg
     fi
     build_jpeg
     build_libpng
@@ -40,8 +36,6 @@ function pre_build {
 tests = True
 toolkits_tests = True
 
-[rc_options]
-backend = $default_backend
 EOF
 }