diff --git a/src/openvpnserv/interactive.c b/src/openvpnserv/interactive.c
index 33282c63..f64c247 100644
--- a/src/openvpnserv/interactive.c
+++ b/src/openvpnserv/interactive.c
@@ -734,9 +734,8 @@
 
     err_str = L"Unknown Win32 Error";
 
-    if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM
-                          | FORMAT_MESSAGE_ARGUMENT_ARRAY,
-                      NULL, err, 0, buf, sizeof(buf), NULL))
+    if (FormatMessageW(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM,
+                       NULL, err, 0, buf, _countof(buf), NULL))
     {
         err_str = buf;
     }