diff --git a/tinygrad/runtime/ops_metal.py b/tinygrad/runtime/ops_metal.py
index c7702b86cc..b749199778 100644
--- a/tinygrad/runtime/ops_metal.py
+++ b/tinygrad/runtime/ops_metal.py
@@ -3,7 +3,7 @@ import os, subprocess, pathlib, ctypes, tempfile, functools
 import Metal, libdispatch
 from typing import List, Set, Any, Tuple, Optional
 from tinygrad.helpers import prod, getenv, DEBUG, unwrap2
-from tinygrad.device import Compiled, Compiler, LRUAllocator
+from tinygrad.device import Compiled, Compiler, CompileError, LRUAllocator
 from tinygrad.renderer.cstyle import MetalRenderer
 
 def wait_check(cbuf: Any):
@@ -23,7 +23,8 @@ class MetalCompiler(Compiler):
     else:
       options = Metal.MTLCompileOptions.new()
       options.setFastMathEnabled_(getenv("METAL_FAST_MATH"))
-      library = unwrap2(self.device.device.newLibraryWithSource_options_error_(src, options, None))
+      try: library = unwrap2(self.device.device.newLibraryWithSource_options_error_(src, options, None))
+      except AssertionError as e: raise CompileError(e)
       return library.libraryDataContents().bytes().tobytes()
 
 class MetalProgram: