diff --git a/src/zmalloc.c b/src/zmalloc.c
index bd36654fb000f17f0df1e11769351606169740f7..11616e5adb9f62605f365a9c4b18dbe3a1be4f97 100644
--- a/src/zmalloc.c
+++ b/src/zmalloc.c
@@ -67,7 +67,10 @@ void zlibc_free(void *ptr) {
 #define free(ptr) je_free(ptr)
 #endif
 
-#ifdef HAVE_ATOMIC
+#if defined(__ATOMIC_RELAXED)
+#define update_zmalloc_stat_add(__n) __atomic_add_fetch(&used_memory, (__n), __ATOMIC_RELAXED)
+#define update_zmalloc_stat_sub(__n) __atomic_sub_fetch(&used_memory, (__n), __ATOMIC_RELAXED)
+#elif defined(HAVE_ATOMIC)
 #define update_zmalloc_stat_add(__n) __sync_add_and_fetch(&used_memory, (__n))
 #define update_zmalloc_stat_sub(__n) __sync_sub_and_fetch(&used_memory, (__n))
 #else
@@ -219,7 +222,7 @@ size_t zmalloc_used_memory(void) {
     size_t um;
 
     if (zmalloc_thread_safe) {
-#ifdef HAVE_ATOMIC
+#if defined(__ATOMIC_RELAXED) || defined(HAVE_ATOMIC)
         um = update_zmalloc_stat_add(0);
 #else
         pthread_mutex_lock(&used_memory_mutex);