diff --git a/windows/NTMakefile.config b/windows/NTMakefile.config
index cea260ace..7fe373a94 100644
--- a/windows/NTMakefile.config
+++ b/windows/NTMakefile.config
@@ -33,6 +33,9 @@ HAVE_INT64_T=1
 # Enable Kerberos v5 support in applications
 KRB5=1
 
+# Enable KX509 support in the KDC
+KX509=1
+
 # Enable PKINIT
 PKINIT=1