--- a/configure.in
+++ b/configure.in
@@ -3,7 +3,9 @@
 AC_CANONICAL_SYSTEM
 
 AM_INIT_AUTOMAKE(vsound, 0.5)
-AM_CONFIG_HEADER(config.h)
+AC_CONFIG_HEADERS(config.h)
+
+AC_CONFIG_MACRO_DIR([.])
 
 AC_PROG_CC
 AC_PROG_CPP
@@ -45,12 +47,12 @@
 fi
 
 if test "$ac_cv_prog_gcc" = yes ; then
-	CFLAGS="-g -O2 -Wall -Wstrict-prototypes -pipe"
+	CFLAGS+=" -Wall -Wstrict-prototypes"
 fi
 
 if test "$ac_arg_debug" = yes; then
 	echo "enabling debug"
-	CFLAGS="$CFLAGS -DENABLE_DEBUG "
+	CPPFLAGS+=" -DENABLE_DEBUG"
 fi
 
 AC_OUTPUT(Makefile vsound)