diff --git a/configure.ac b/configure.ac
index 2e3409bc3..537e9dc59 100644
--- a/configure.ac
+++ b/configure.ac
@@ -92,6 +92,7 @@ AC_PROG_CXX([g++ c++])
 AC_PROG_INSTALL
 AC_PROG_SED
 AC_LANG(C++)
+AC_USE_SYSTEM_EXTENSIONS
 
 echo "CXXFLAGS: $CXXFLAGS"