diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1814fb6..f8a862f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -306,6 +306,18 @@ endif()
 check_c_source_compiles ("int main() { unsigned long val; __sync_bool_compare_and_swap(&val, 0, 1); __sync_add_and_fetch(&val, 1); __sync_sub_and_fetch(&val, 1); return 0; } " HAVE_SYNC_BUILTINS)
 check_c_source_compiles ("int main() { char l; unsigned long v; __atomic_test_and_set(&l, __ATOMIC_RELAXED); __atomic_store_n(&v, 1, __ATOMIC_RELEASE); __atomic_load_n(&v, __ATOMIC_ACQUIRE); __atomic_add_fetch(&v, 1, __ATOMIC_ACQUIRE); __atomic_sub_fetch(&v, 1, __ATOMIC_RELEASE); return 0; }" HAVE_ATOMIC_BUILTINS)
 
+if (HAVE_SYNC_BUILTINS)
+  set(JSON_HAVE_SYNC_BUILTINS 1)
+else()
+  set(JSON_HAVE_SYNC_BUILTINS 0)
+endif()
+
+if (HAVE_ATOMIC_BUILTINS)
+  set(JSON_HAVE_ATOMIC_BUILTINS 1)
+else()
+  set(JSON_HAVE_ATOMIC_BUILTINS 0)
+endif()
+
 set (JANSSON_INITIAL_HASHTABLE_ORDER 3 CACHE STRING "Number of buckets new object hashtables contain is 2 raised to this power. The default is 3, so empty hashtables contain 2^3 = 8 buckets.")
 
 # configure the public config file
diff --git a/cmake/jansson_config.h.cmake b/cmake/jansson_config.h.cmake
index f703dcb..2f248cb 100644
--- a/cmake/jansson_config.h.cmake
+++ b/cmake/jansson_config.h.cmake
@@ -59,10 +59,16 @@
 /* If locale.h and localeconv() are available, define to 1, otherwise to 0. */
 #define JSON_HAVE_LOCALECONV @JSON_HAVE_LOCALECONV@
 
+/* If __atomic builtins are available they will be used to manage
+   reference counts of json_t. */
+#define JSON_HAVE_ATOMIC_BUILTINS @JSON_HAVE_ATOMIC_BUILTINS@
+
+/* If __atomic builtins are not available we try using __sync builtins
+   to manage reference counts of json_t. */
+#define JSON_HAVE_SYNC_BUILTINS @JSON_HAVE_SYNC_BUILTINS@
 
 /* Maximum recursion depth for parsing JSON input.
    This limits the depth of e.g. array-within-array constructions. */
 #define JSON_PARSER_MAX_DEPTH 2048
 
-
 #endif