--- configure.ac
+++ configure.ac
@@ -7,10 +7,6 @@
 
 AM_CONFIG_HEADER([uim/config.h])
 
-# Set empty values to cancel default "-g -O2"
-CFLAGS=""
-CXXFLAGS=""
-
 # Checks for programs.
 AC_PROG_CXX
 AC_PROG_CC
@@ -238,10 +234,10 @@
 
 LIBDIR=`eval echo ${libdir}`
 AC_DEFINE_UNQUOTED(LIBDIR, "$LIBDIR", [libraries dir])
-DATADIR=`eval echo ${datadir}`
+eval eval DATADIR=${datadir}
 AC_DEFINE_UNQUOTED(DATADIR, "$DATADIR", [read-only architecture-independent data dir])
 # we should use more safe macro such as AC_EXPAND_DIR
-LOCALEDIR=`eval echo ${datadir}/locale`
+eval eval LOCALEDIR=${datadir}/locale
 # backward compatibility
 localedir=$LOCALEDIR
 AC_DEFINE_UNQUOTED(LOCALEDIR, "$LOCALEDIR", [locale dir])