diff --git a/configure.ac b/configure.ac
index e838891..793931e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -28,15 +28,17 @@ dnl  **************************************
 dnl ***** tests for compiler built-ins *****
 dnl  **************************************
 
-AC_CACHE_CHECK([for __sync_bool_compare_and_swap_8],
-[ctrie_cv_func___sync_bool_compare_and_swap_8],
-[AC_LINK_IFELSE([
-typedef unsigned int uint64  __attribute__ ((mode (DI)));
-uint64 i;
-int main() { return __sync_bool_compare_and_swap (&i, 0, 1); }
-],
-[ctrie_cv_func___sync_bool_compare_and_swap_8=yes],
-[ctrie_cv_func___sync_bool_compare_and_swap_8=no])])
+AC_CACHE_CHECK(
+  [for __sync_bool_compare_and_swap_8],
+  [ctrie_cv_func___sync_bool_compare_and_swap_8],
+  [AC_LINK_IFELSE([AC_LANG_SOURCE([
+    typedef unsigned int uint64  __attribute__ ((mode (DI)));
+    uint64 i;
+    int main() { return __sync_bool_compare_and_swap (&i, 0, 1); }
+  ])],
+  [ctrie_cv_func___sync_bool_compare_and_swap_8=yes],
+  [ctrie_cv_func___sync_bool_compare_and_swap_8=no])])
+  
 if test "$ctrie_cv_func___sync_bool_compare_and_swap_8" = "yes"; then
   AC_DEFINE([HAVE__SYNC_BOOL_COMPARE_AND_SWAP_8], 1,
     [Define to 1 if the compiler provides the __sync_bool_compare_and_swap function for uint64])