diff --git a/configure.ac b/configure.ac
index 2b20543..7b4acb5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -160,21 +160,21 @@ else
     AC_MSG_NOTICE([optimization disabled (default)])
 fi
 
-if test "x$enable_cxx0" != 'xno'
-then
-    AC_MSG_NOTICE([c++x0 dialect is enabled (default), compilation with "-DHAVE_CXX0 -std=c++0x "])
-    CPPFLAGS="$CPPFLAGS -DHAVE_CXX0 -std=c++0x";
-else
-    AC_MSG_NOTICE([c++x0 dialect is disabled, compilation without "-std=c++0x" and with "-UHAVE_CXX0"])
-    CPPFLAGS="$CPPFLAGS -UHAVE_CXX0";
-fi
-
 if test "x$with_zlib" != 'xno'
 then
   CPPFLAGS="$CPPFLAGS -I${with_zlib}/include"
   LDFLAGS="$LDFLAGS -L${with_zlib}/lib"
 fi
 
+if test "x$enable_cxx0" != 'xno'
+then
+    AC_MSG_NOTICE([c++x0 dialect is enabled (default), compilation with "-DHAVE_CXX0 -std=c++0x "])
+    CXXFLAGS="$CXXFLAGS -DHAVE_CXX0 -std=c++0x";
+else
+    AC_MSG_NOTICE([c++x0 dialect is disabled, compilation without "-std=c++0x" and with "-UHAVE_CXX0"])
+    CXXFLAGS="$CXXFLAGS -UHAVE_CXX0";
+fi
+
 LIBS="$LIBS -lz"
 
 AC_CONFIG_FILES([
diff --git a/src/Makefile.am b/src/Makefile.am
index 6169e64..e08adbc 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,6 +1,6 @@
 lib_LTLIBRARIES = libirstlm.la
 
-AM_CXXFLAGS = -static -isystem/usr/include -W -Wall -ffor-scope -D_FILE_OFFSET_BITS=64 -D_LARGE_FILES $(BOOST_CPPFLAGS) -DMYCODESIZE=3
+AM_CXXFLAGS = -static -W -Wall -ffor-scope -D_FILE_OFFSET_BITS=64 -D_LARGE_FILES $(BOOST_CPPFLAGS) -DMYCODESIZE=3
 
 libirstlm_ladir = ${includedir}