diff --git a/ChangeLog b/ChangeLog
index eaf4b5f72ee9948c52faaf72d52fd83ced320cc3..90e25e943f5ba796e0f672df57e19b76ad9d85dc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2013-01-12  Niels Möller  <nisse@lysator.liu.se>
+
+	* configure.ac: Use AC_LANG_SOURCE.
+
 2013-01-02  Niels Möller  <nisse@lysator.liu.se>
 
 	* configure.ac (LIBNETTLE_MINOR): Bumped library version, to 4.5.
diff --git a/configure.ac b/configure.ac
index 3943d72ddf84b87e7c31d46112ab74c84f5c303c..e851ad0caa9753665e4702cf14e7d46ee26ff028 100644
--- a/configure.ac
+++ b/configure.ac
@@ -380,7 +380,7 @@ if test x$enable_assembler = xyes ; then
   [ # Default is no underscore
     nettle_cv_asm_underscore=no
     AC_COMPILE_IFELSE(
-      [int a_global_symbol;],
+      [AC_LANG_SOURCE([int a_global_symbol;])],
       [ $NM conftest.$OBJEXT >conftest.out
         if grep _a_global_symbol conftest.out >/dev/null ; then
           nettle_cv_asm_underscore=yes