diff --git a/actions/openvpn b/actions/openvpn
index 6b4629843..464b151b5 100755
--- a/actions/openvpn
+++ b/actions/openvpn
@@ -25,7 +25,7 @@ import subprocess
 
 import augeas
 
-from plinth import action_utils
+from plinth import action_utils, utils
 
 KEYS_DIRECTORY = '/etc/openvpn/freedombox-keys'
 
@@ -120,7 +120,7 @@ def parse_arguments():
 
 def subcommand_is_setup(_):
     """Return whether setup is complete."""
-    print('true' if os.path.isfile(DH_KEY) else 'false')
+    print('true' if utils.is_non_empty_file(DH_KEY) else 'false')
 
 
 def subcommand_setup(_):
diff --git a/plinth/utils.py b/plinth/utils.py
index b139bd574..052a08f86 100644
--- a/plinth/utils.py
+++ b/plinth/utils.py
@@ -154,3 +154,7 @@ def gunzip(gzip_file, output_file):
 
     with open(output_file, 'wb', opener=opener) as file_handle:
         file_handle.write(contents)
+
+
+def is_non_empty_file(file_path):
+    return os.path.isfile(file_path) and os.path.getsize(file_path) > 0