diff --git a/cf/krb-bigendian.m4 b/cf/krb-bigendian.m4
index 62af3ffdf..e8037503f 100644
--- a/cf/krb-bigendian.m4
+++ b/cf/krb-bigendian.m4
@@ -51,7 +51,7 @@ if test "$krb_cv_c_bigendian_compile" = "yes"; then
   AC_DEFINE(ENDIANESS_IN_SYS_PARAM_H, 1, [define if sys/param.h defines the endiness])dnl
 fi
 AH_BOTTOM([
-#if ENDIANESS_IN_SYS_PARAM_H
+#ifdef ENDIANESS_IN_SYS_PARAM_H
 #  include <sys/types.h>
 #  include <sys/param.h>
 #  if BYTE_ORDER == BIG_ENDIAN