diff --git a/extra/optimization/helpers.py b/extra/optimization/helpers.py
index 2b51ba3cb7..cda0916418 100644
--- a/extra/optimization/helpers.py
+++ b/extra/optimization/helpers.py
@@ -10,7 +10,7 @@ inf, nan = float('inf'), float('nan')
 
 # kernel unpacker
 from tinygrad.codegen.kernel import Kernel
-def ast_str_to_ast(ast_str:str) -> Tuple[LazyOp,...]: return LazyOp(MetaOps.SINK, val) if isinstance(val:=eval(ast_str), tuple) else val
+def ast_str_to_ast(ast_str:str) -> LazyOp: return LazyOp(MetaOps.SINK, val) if isinstance(val:=eval(ast_str), tuple) else val
 def ast_str_to_lin(ast_str:str, opts=None): return Kernel(ast_str_to_ast(ast_str), opts=opts)
 def kern_str_to_lin(kern_str:str, opts=None):
   (ast, applied_opts,) = eval(kern_str)
diff --git a/test/external/fuzz_linearizer.py b/test/external/fuzz_linearizer.py
index 319830c873..25f0a89b7c 100644
--- a/test/external/fuzz_linearizer.py
+++ b/test/external/fuzz_linearizer.py
@@ -2,7 +2,7 @@ import random, traceback, ctypes, argparse
 from typing import List, Tuple, DefaultDict
 import numpy as np
 from collections import defaultdict
-from extra.optimization.helpers import load_worlds, ast_str_to_lin
+from extra.optimization.helpers import load_worlds, ast_str_to_lin, kern_str_to_lin
 
 from tinygrad import Tensor, Device, dtypes
 from tinygrad.tensor import _to_np_dtype
@@ -157,7 +157,14 @@ def fuzz_linearizer(lin: Kernel, rtol=1e-2, atol=1e-2):
         if not FUZZ_ALL_ACTIONS and test_lin.applied_opts: print(f"applied opts: {test_lin.applied_opts}")
 
         # stop if kernel uops repeat
-        tuops = tuplize_uops(test_lin.linearize().uops.uops)
+        try: tuops = tuplize_uops(test_lin.linearize().uops.uops)
+        except BaseException as e:
+          print(test_lin.ast)
+          print(test_lin.applied_opts)
+          print(e)
+          failures["LINEARIZE_ERROR"].append((test_lin.ast, test_lin.applied_opts))
+          continue
+
         if tuops in seen_uops: continue
         seen_uops[tuops] = tuple(test_lin.applied_opts)
 
@@ -187,6 +194,7 @@ if __name__ == "__main__":
   parser = argparse.ArgumentParser(description="Run a fuzz testing on one or more kernels", formatter_class=argparse.ArgumentDefaultsHelpFormatter)
   parser.add_argument("--ast", type=str, default=None, help="the ast for the kernel to be optimized")
   parser.add_argument("--file", type=str, default=None, help="a file containing asts to be optimized, one per line")
+  parser.add_argument("--logfile", type=str, default=None, help="a file containing a tuple of ast and applied_opts, one per line")
   parser.add_argument("--expected-failures", type=int, default=0, help="the number of expected failed kernels")
   parser.add_argument("--rtol", type=float, default=1e-2, help="relative tolerance for numerical comparison")
   parser.add_argument("--atol", type=float, default=1e-2, help="absolute tolerance for numerical comparison")
@@ -199,6 +207,12 @@ if __name__ == "__main__":
     print(f"loading ASTs from file '{args.file}'")
     with open(args.file, 'r') as file:
       ast_strs = file.readlines()
+  elif args.logfile is not None:
+    print(f"loading ASTs from LOGKERNS file '{args.file}'")
+    with open(args.logfile, 'r') as file:
+      kern_strs = file.readlines()
+      test_lins = [kern_str_to_lin(kern_str) for kern_str in kern_strs]
+      ast_strs = [f"{lin.ast}" for lin in test_lins]
   else:
     print("loading ASTs from world")
     ast_strs = load_worlds(filter_reduce=False, filter_novariable=False)
diff --git a/test/external/verify_kernel.py b/test/external/verify_kernel.py
index c614bfad6c..c9f34b2527 100644
--- a/test/external/verify_kernel.py
+++ b/test/external/verify_kernel.py
@@ -51,9 +51,8 @@ if __name__ == "__main__":
   failures = defaultdict(list)
   for i, test_lin in enumerate(test_lins):
     print(f"testing kernel {i}")
-    for op in test_lin.ast:
-      print_tree(op)
-      print(op)
+    print_tree(test_lin.ast)
+    print(test_lin.ast)
     print(test_lin.applied_opts)
     unoptimized_lin = Kernel(test_lin.ast)
     unoptimized_lin.required_optimizations()
diff --git a/test/test_linearizer_failures.py b/test/test_linearizer_failures.py
index d9ccb798ad..db1cb7bfd0 100644
--- a/test/test_linearizer_failures.py
+++ b/test/test_linearizer_failures.py
@@ -280,5 +280,37 @@ class TestLinearizerFailures(unittest.TestCase):
     opts = [Opt(op=OptOps.GROUPTOP, axis=0, amt=16)]
     helper_test_lin(Kernel(ast), opts=opts, failed_platforms=["METAL", "GPU", "CUDA", "AMD", "NV"])
 
+  # from world fuzz_linearizer: PYTHONPATH=. METAL=1 FUZZ_ALL_ACTIONS=1 DEPTH=1 FUZZ_N=100 FUZZ_NTH=84 python3 ./test/external/fuzz_linearizer.py
+  def test_failure_36(self):
+    # UOps.UNMUL left after linearize
+    ast = LazyOp(op=MetaOps.SINK, src=(LazyOp(op=BufferOps.STORE, src=(LazyOp(op=UnaryOps.CAST, src=(LazyOp(op=BinaryOps.ADD, src=(LazyOp(op=ReduceOps.SUM, src=(LazyOp(op=UnaryOps.CAST, src=(LazyOp(op=BufferOps.CONST, src=(), arg=ConstBuffer(val=1, dtype=dtypes.uchar, st=ShapeTracker(views=(View(shape=(6, 9), strides=(0, 0), offset=0, mask=((0, 6), (4, 9)), contiguous=False), View(shape=(5, 5), strides=(1, 10), offset=0, mask=None, contiguous=False))))),), arg=dtypes.uint),), arg=(1,)), LazyOp(op=BufferOps.CONST, src=(), arg=ConstBuffer(val=-1, dtype=dtypes.uint, st=ShapeTracker(views=(View(shape=(5, 1), strides=(0, 0), offset=0, mask=None, contiguous=False),))))), arg=None),), arg=dtypes.uchar),), arg=MemBuffer(idx=0, dtype=dtypes.uchar, st=ShapeTracker(views=(View(shape=(5, 1), strides=(1, 0), offset=0, mask=None, contiguous=True),)))),), arg=None)
+    opts = [Opt(op=OptOps.UPCAST, axis=0, amt=0)]
+    helper_test_lin(Kernel(ast), opts=opts, failed_platforms=["METAL", "GPU", "CUDA", "AMD", "NV", "CLANG", "LLVM"])
+
+  # BEGIN METAL=1 ./examples/beautiful_mnist.py failures
+  # log : PYTHONPATH=. LOGKERNS=/tmp/beautiful_mnist.kernels.txt METAL=1 python3 ./examples/beautiful_mnist.py
+  def test_failure_37(self):
+    # beautiful mnist kernel number 28: 6 possible TC axis_choices (3 for axis_buf1 and 2 reduce) and all fail
+    # fuzz: PYTHONPATH=. METAL=1 FUZZ_ALL_ACTIONS=1 DEPTH=1 FUZZ_NTH=28 DEBUG=2 python3 ./test/external/fuzz_linearizer.py --logfile /tmp/beautiful_mnist.kernels.txt
+    ast = LazyOp(op=MetaOps.SINK, src=(LazyOp(op=BufferOps.STORE, src=(LazyOp(op=BinaryOps.MAX, src=(LazyOp(op=BinaryOps.ADD, src=(LazyOp(op=ReduceOps.SUM, src=(LazyOp(op=BinaryOps.MUL, src=(LazyOp(op=UnaryOps.CAST, src=(LazyOp(op=BufferOps.LOAD, src=(), arg=MemBuffer(idx=1, dtype=dtypes.uchar, st=ShapeTracker(views=(View(shape=(512, 1, 32, 24, 24, 1, 5, 5), strides=(784, 0, 0, 28, 1, 0, 28, 1), offset=0, mask=None, contiguous=False),)))),), arg=dtypes.float), LazyOp(op=BufferOps.LOAD, src=(), arg=MemBuffer(idx=2, dtype=dtypes.float, st=ShapeTracker(views=(View(shape=(512, 1, 32, 24, 24, 1, 5, 5), strides=(0, 0, 25, 0, 0, 0, 5, 1), offset=0, mask=None, contiguous=False),))))), arg=None),), arg=(6, 7)), LazyOp(op=BufferOps.LOAD, src=(), arg=MemBuffer(idx=3, dtype=dtypes.float, st=ShapeTracker(views=(View(shape=(512, 1, 32, 24, 24, 1, 1, 1), strides=(0, 0, 1, 0, 0, 0, 0, 0), offset=0, mask=None, contiguous=False),))))), arg=None), LazyOp(op=BufferOps.CONST, src=(), arg=ConstBuffer(val=0.0, dtype=dtypes.float, st=ShapeTracker(views=(View(shape=(512, 1, 32, 24, 24, 1, 1, 1), strides=(0, 0, 0, 0, 0, 0, 0, 0), offset=0, mask=None, contiguous=False),))))), arg=None),), arg=MemBuffer(idx=0, dtype=dtypes.float, st=ShapeTracker(views=(View(shape=(512, 1, 32, 24, 24, 1, 1, 1), strides=(18432, 0, 576, 24, 1, 0, 0, 0), offset=0, mask=None, contiguous=True),)))),), arg=None)
+    for axis in [0,1,2,3,4,5]:
+      opts = [Opt(op=OptOps.TC, axis=axis, amt=2)]
+      helper_test_lin(Kernel(ast), opts=opts, failed_platforms=["METAL"])
+  def test_failure_38(self):
+    # beautiful mnist kernel number 87: 6 possible TC axis_choices (2 for axis_buf1 and 3 reduce) and first/second reduce axis fail for both axis_buf1 choices
+    # fuzz: PYTHONPATH=. METAL=1 FUZZ_ALL_ACTIONS=1 DEPTH=1 FUZZ_NTH=87 DEBUG=2 python3 ./test/external/fuzz_linearizer.py --logfile /tmp/beautiful_mnist.kernels.txt
+    ast = LazyOp(op=MetaOps.SINK, src=(LazyOp(op=BufferOps.STORE, src=(LazyOp(op=ReduceOps.SUM, src=(LazyOp(op=BinaryOps.MUL, src=(LazyOp(op=UnaryOps.CAST, src=(LazyOp(op=BufferOps.LOAD, src=(), arg=MemBuffer(idx=1, dtype=dtypes.uchar, st=ShapeTracker(views=(View(shape=(2, 1, 32, 24, 24, 1, 5, 5, 256), strides=(784, 0, 0, 28, 1, 0, 28, 1, 1568), offset=0, mask=None, contiguous=False),)))),), arg=dtypes.float), LazyOp(op=BufferOps.LOAD, src=(), arg=MemBuffer(idx=2, dtype=dtypes.float, st=ShapeTracker(views=(View(shape=(2, 1, 32, 24, 24, 1, 5, 5, 256), strides=(18432, 0, 576, 24, 1, 0, 0, 0, 36864), offset=0, mask=None, contiguous=False),))))), arg=None),), arg=(0, 3, 4)),), arg=MemBuffer(idx=0, dtype=dtypes.float, st=ShapeTracker(views=(View(shape=(1, 1, 32, 1, 1, 1, 5, 5, 256), strides=(0, 0, 6400, 0, 0, 0, 1280, 256, 1), offset=0, mask=None, contiguous=True),)))),), arg=None)
+    for axis in [0,1,3,4]:
+      opts = [Opt(op=OptOps.TC, axis=axis, amt=2)]
+      helper_test_lin(Kernel(ast), opts=opts, failed_platforms=["METAL"])
+  def test_failure_39(self):
+    # beautiful mnist kernel number 127: 6 possible TC axis_choices (3 for axis_buf1 and 2 reduce) and all fail
+    # fuzz: PYTHONPATH=. METAL=1 FUZZ_ALL_ACTIONS=1 DEPTH=1 FUZZ_NTH=127 DEBUG=2 python3 ./test/external/fuzz_linearizer.py --logfile /tmp/beautiful_mnist.kernels.txt
+    ast = LazyOp(op=MetaOps.SINK, src=(LazyOp(op=BufferOps.STORE, src=(LazyOp(op=BinaryOps.MAX, src=(LazyOp(op=BinaryOps.ADD, src=(LazyOp(op=ReduceOps.SUM, src=(LazyOp(op=BinaryOps.MUL, src=(LazyOp(op=UnaryOps.CAST, src=(LazyOp(op=BufferOps.LOAD, src=(), arg=MemBuffer(idx=1, dtype=dtypes.uchar, st=ShapeTracker(views=(View(shape=(10000, 1, 32, 24, 24, 1, 5, 5), strides=(784, 0, 0, 28, 1, 0, 28, 1), offset=0, mask=None, contiguous=False),)))),), arg=dtypes.float), LazyOp(op=BufferOps.LOAD, src=(), arg=MemBuffer(idx=2, dtype=dtypes.float, st=ShapeTracker(views=(View(shape=(10000, 1, 32, 24, 24, 1, 5, 5), strides=(0, 0, 25, 0, 0, 0, 5, 1), offset=0, mask=None, contiguous=False),))))), arg=None),), arg=(6, 7)), LazyOp(op=BufferOps.LOAD, src=(), arg=MemBuffer(idx=3, dtype=dtypes.float, st=ShapeTracker(views=(View(shape=(10000, 1, 32, 24, 24, 1, 1, 1), strides=(0, 0, 1, 0, 0, 0, 0, 0), offset=0, mask=None, contiguous=False),))))), arg=None), LazyOp(op=BufferOps.CONST, src=(), arg=ConstBuffer(val=0.0, dtype=dtypes.float, st=ShapeTracker(views=(View(shape=(10000, 1, 32, 24, 24, 1, 1, 1), strides=(0, 0, 0, 0, 0, 0, 0, 0), offset=0, mask=None, contiguous=False),))))), arg=None),), arg=MemBuffer(idx=0, dtype=dtypes.float, st=ShapeTracker(views=(View(shape=(10000, 1, 32, 24, 24, 1, 1, 1), strides=(18432, 0, 576, 24, 1, 0, 0, 0), offset=0, mask=None, contiguous=True),)))),), arg=None)
+    for axis in [0,1,2,3,4,5]:
+      opts = [Opt(op=OptOps.TC, axis=axis, amt=2)]
+      helper_test_lin(Kernel(ast), opts=opts, failed_platforms=["METAL"])
+  # END METAL=1 ./examples/beautiful_mnist.py failures
+
 if __name__ == '__main__':
   unittest.main()