diff --git a/m4/check-package.m4 b/m4/check-package.m4
index 6bb1432ec742449225f341b21597cd075f4084ed..717c5c0be7de1f2aba75e2a515a1cafa3233102f 100644
--- a/m4/check-package.m4
+++ b/m4/check-package.m4
@@ -29,7 +29,7 @@ AC_HELP_STRING([--without-$1], [disable use of package $1
 	[m4_bpatsubst([$1],-,_)_DISABLE=no])
 ])
 AC_DEFUN(ALBERT_CHECK_PACKAGE,
-[dnl AC_REQUIRE([AC_SET_PREFIX])
+[AC_REQUIRE([AC_SET_PREFIX])
 dnl
 m4_if($7, optional,[ALBERT_CHECK_PKG_OPT([$1])])
 dnl if test "$7" = "optional"; then