diff --git a/build.xml b/build.xml
index 564e134a..ee1154c6 100644
--- a/build.xml
+++ b/build.xml
@@ -158,14 +158,6 @@
     <property name="md.wayf.signed"     value="ukfederation-wayf.xml"/>
     <property name="md.cdsall.signed"   value="ukfederation-cdsall.xml"/>
 
-    <!--
-        Null device location.
-    -->
-    <condition property="null.device"
-        value="nul:" else="/dev/null">
-        <os family="windows"/>
-    </condition>
-
     <!--
         Signing keystore alias.
     -->
diff --git a/default.properties b/default.properties
index 1c10546b..52e37c07 100644
--- a/default.properties
+++ b/default.properties
@@ -5,3 +5,6 @@
 # here may be overridden in platform-specific properties files,
 # or in a machine-specific build.properties file.
 #
+
+# Null device location.
+null.device=/dev/null
diff --git a/windows.properties b/windows.properties
index 2a29a5b6..69e6648c 100644
--- a/windows.properties
+++ b/windows.properties
@@ -6,6 +6,9 @@
 # properties defined in a machine-specific build.properties file.
 #
 
+# Null device location.
+null.device=nul:
+
 #
 # Location of the PKCS#11 configuration file for an ACOS5 card.
 #