diff --git a/cf/check-xau.m4 b/cf/check-xau.m4
index 553881137..f66e2d193 100644
--- a/cf/check-xau.m4
+++ b/cf/check-xau.m4
@@ -16,12 +16,12 @@ LDFLAGS="$LDFLAGS $X_LIBS"
 ## could be done by checking for XauReadAuth in -lXau first, but this
 ## breaks in IRIX 6.5
 
-AC_FIND_FUNC_NO_LIBS(XauWriteAuth, X11 Xau)
+AC_FIND_FUNC_NO_LIBS(XauWriteAuth, X11 Xau,[#include <X11/Xauth.h>],[0,0])
 ac_xxx="$LIBS"
 LIBS="$LIB_XauWriteAuth $LIBS"
-AC_FIND_FUNC_NO_LIBS(XauReadAuth, X11 Xau)
+AC_FIND_FUNC_NO_LIBS(XauReadAuth, X11 Xau,[#include <X11/Xauth.h>],[0])
 LIBS="$LIB_XauReadAauth $LIBS"
-AC_FIND_FUNC_NO_LIBS(XauFileName, X11 Xau)
+AC_FIND_FUNC_NO_LIBS(XauFileName, X11 Xau,[#include <X11/Xauth.h>])
 LIBS="$ac_xxx"
 
 ## set LIB_XauReadAuth to union of these tests, since this is what the