diff --git a/configure.ac b/configure.ac
index 1b99702f..3a24053b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -55,6 +55,8 @@ if test "$sys_name" = sunos; then
 fi
 
 
+CFLAGS=
+CXXFLAGS=
 AC_PROG_CC
 AC_PROG_CXX