diff --git a/configure.ac b/configure.ac
index de3e98418..618c3f15c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -140,8 +140,8 @@ AC_SEARCH_LIBS([socket], [socket])
 AC_SEARCH_LIBS([gethostbyname], [nsl])
 
 AC_CHECK_FUNCS(pipe2 accept4)
-MPD_OPTIONAL_FUNC(eventfd, USE_EVENTFD)
-MPD_OPTIONAL_FUNC(signalfd, USE_SIGNALFD)
+MPD_OPTIONAL_FUNC(eventfd, eventfd, USE_EVENTFD)
+MPD_OPTIONAL_FUNC(signalfd, signalfd, USE_SIGNALFD)
 
 AC_SEARCH_LIBS([exp], [m],,
 	[AC_MSG_ERROR([exp() not found])])
diff --git a/m4/mpd_func.m4 b/m4/mpd_func.m4
index c4650336b..d12d27062 100644
--- a/m4/mpd_func.m4
+++ b/m4/mpd_func.m4
@@ -1,12 +1,12 @@
-dnl MPD_OPTIONAL_FUNC(func, macro)
+dnl MPD_OPTIONAL_FUNC(name, func, macro)
 dnl
 dnl Allow the user to enable or disable the use of a function.  If the
 dnl option is not specified, the function is auto-detected.
 AC_DEFUN([MPD_OPTIONAL_FUNC], [
 	AC_ARG_ENABLE([$1],
 		AS_HELP_STRING([--enable-$1],
-			[use the function "$1()" (default: auto)]),
-		[test xenable_$1 = xyes && AC_DEFINE([$2], 1, [Define to use $1()])],
-		[AC_CHECK_FUNC([$1],
-			[AC_DEFINE([$2], 1, [Define to use $1()])],)])
+			[use the function "$1" (default: auto)]),
+		[test xenable_$1 = xyes && AC_DEFINE([$3], 1, [Define to use $1])],
+		[AC_CHECK_FUNC([$2],
+			[AC_DEFINE([$3], 1, [Define to use $1])],)])
 ])