diff --git a/ggml.c b/ggml.c
index b65f70439..48dc90cba 100644
--- a/ggml.c
+++ b/ggml.c
@@ -60,6 +60,9 @@
 
 typedef volatile LONG atomic_int;
 typedef atomic_int atomic_bool;
+typedef atomic_int atomic_flag;
+
+#define ATOMIC_FLAG_INIT 0
 
 static void atomic_store(atomic_int * ptr, LONG val) {
     InterlockedExchange(ptr, val);
@@ -73,6 +76,12 @@ static LONG atomic_fetch_add(atomic_int * ptr, LONG inc) {
 static LONG atomic_fetch_sub(atomic_int * ptr, LONG dec) {
     return atomic_fetch_add(ptr, -(dec));
 }
+static atomic_bool atomic_flag_test_and_set(atomic_flag * ptr) {
+    return InterlockedExchange(ptr, 1);
+}
+static void atomic_flag_clear(atomic_flag * ptr) {
+    InterlockedExchange(ptr, 0);
+}
 
 typedef HANDLE pthread_t;