diff --git a/refpolicy/policy/support/misc_macros.spt b/refpolicy/policy/support/misc_macros.spt
index bae5d97..3471b66 100644
--- a/refpolicy/policy/support/misc_macros.spt
+++ b/refpolicy/policy/support/misc_macros.spt
@@ -12,6 +12,13 @@
 define(`shiftn',`ifelse($1,0,`shift($*)',`shiftn(decr($1),shift(shift($*)))')')
 
 #
+# ifndef(expr,true_block,false_block)
+#
+# m4 does not have this.
+#
+define(`ifndef',`ifdef(`$1',`$3',`$2')')
+
+#
 # __endline__
 #
 # dummy macro to insert a newline.  used for