diff --git a/configure.in b/configure.in
index 7dcf6bb..d31cb07 100644
--- a/configure.in
+++ b/configure.in
@@ -588,6 +588,7 @@ fi
 
 AM_CONDITIONAL(CDTYPE_WIN32, test "$CDTYPE" = "WIN32")
 AM_CONDITIONAL(CDTYPE_LINUX, test "$CDTYPE" = "LINUX")
+AM_CONDITIONAL(CDTYPE_NULL, test "$CDTYPE" != "WIN32" -a "$CDTYPE" != "LINUX")
 
 
 dnl ==================================================================
diff --git a/source/Makefile.am b/source/Makefile.am
index f2e61a8..363a80f 100644
--- a/source/Makefile.am
+++ b/source/Makefile.am
@@ -22,25 +22,23 @@ EXTRA_libqfsys_sv_a_SOURCES = sv_sys_unix.c sv_sys_win.c sys_win.c sys_unix.c fn
 
 if SNDTYPE_WIN32
 libqfsnd_a_SOURCES = snd_win.c
-else
+endif
 if SNDTYPE_OSS
 libqfsnd_a_SOURCES = snd_oss.c
-else
+endif
 if SNDTYPE_ALSA
 libqfsnd_a_SOURCES = snd_alsa.c
 endif
-endif
-endif
 EXTRA_libqfsnd_a_SOURCES = snd_win.c snd_oss.c snd_alsa.c
 
 if CDTYPE_WIN32
 libqfcd_a_SOURCES = cd_win.c
-else
+endif
 if CDTYPE_LINUX
 libqfcd_a_SOURCES = cd_linux.c
-else
-libqfcd_a_SOURCES = cd_null.c
 endif
+if CDTYPE_NULL
+libqfcd_a_SOURCES = cd_null.c
 endif
 EXTRA_libqfcd_a_SOURCES = cd_win.c cd_linux.c cd_null.c