diff --git a/tinygrad/runtime/ops_metal.py b/tinygrad/runtime/ops_metal.py
index 7b364dd3..a4c6a712 100644
--- a/tinygrad/runtime/ops_metal.py
+++ b/tinygrad/runtime/ops_metal.py
@@ -1,6 +1,7 @@
 # pip3 install pyobjc-framework-Metal pyobjc-framework-Cocoa pyobjc-framework-libdispatch
 import os, subprocess, pathlib
 import Metal, Cocoa, libdispatch # type: ignore
+from typing import List, Any
 from tinygrad.codegen.cstyle import CStyleCodegen, CStyleLanguage
 from tinygrad.helpers import prod, getenv, DEBUG, DType
 from tinygrad.ops import Compiled
@@ -10,17 +11,13 @@ METAL_XCODE = getenv("METAL_XCODE")
 
 class _METAL:
   def __init__(self):
+    self.mtl_buffers_in_flight: List[Any] = []
     self.device = Metal.MTLCreateSystemDefaultDevice()
-    self.dispatch_group = libdispatch.dispatch_group_create() 
     self.mtl_queue = self.device.newCommandQueue()
-  def command_buffer(self):
-    command_buffer = self.mtl_queue.commandBuffer()
-    libdispatch.dispatch_group_enter(self.dispatch_group)
-    def leave(_): libdispatch.dispatch_group_leave(self.dispatch_group)
-    command_buffer.addCompletedHandler_(leave)
-    return command_buffer
+  # TODO: is there a better way to do this?
   def synchronize(self):
-    libdispatch.dispatch_group_wait(self.dispatch_group, libdispatch.DISPATCH_TIME_FOREVER)
+    for cbuf in self.mtl_buffers_in_flight: cbuf.waitUntilCompleted()
+    self.mtl_buffers_in_flight.clear()
 METAL = _METAL()
 
 class RawMetalBuffer(RawBufferMapped):
@@ -63,7 +60,7 @@ class MetalProgram:
 
   def __call__(self, global_size, local_size, *bufs, wait=False):
     assert prod(local_size) <= self.pipeline_state.maxTotalThreadsPerThreadgroup(), f"local size {local_size} bigger than {self.pipeline_state.maxTotalThreadsPerThreadgroup()} with exec width {self.pipeline_state.threadExecutionWidth()} memory length {self.pipeline_state.staticThreadgroupMemoryLength()}"
-    command_buffer = METAL.command_buffer()
+    command_buffer = METAL.mtl_queue.commandBuffer()
     encoder = command_buffer.computeCommandEncoder()
     encoder.setComputePipelineState_(self.pipeline_state)
     for i,a in enumerate(bufs): encoder.setBuffer_offset_atIndex_(a._buf, 0, i)
@@ -73,6 +70,7 @@ class MetalProgram:
     if wait:
       command_buffer.waitUntilCompleted()
       return command_buffer.GPUEndTime() - command_buffer.GPUStartTime()
+    METAL.mtl_buffers_in_flight.append(command_buffer)
 
 class MetalCodegen(CStyleCodegen):
   lang = CStyleLanguage(