diff --git a/test/models/test_real_world.py b/test/models/test_real_world.py
index a1f309b2e2..8e7eb7746f 100644
--- a/test/models/test_real_world.py
+++ b/test/models/test_real_world.py
@@ -111,7 +111,7 @@ class TestRealWorld(unittest.TestCase):
         loss.backward()
         optimizer.step()
 
-      helper_test("train_mnist", lambda: (Tensor.randn(BS, 1, 28, 28),), train, 0.07, 63)
+      helper_test("train_mnist", lambda: (Tensor.randn(BS, 1, 28, 28),), train, 0.07, 104)
 
   @unittest.skipIf(CI and Device.DEFAULT in {"CLANG", "GPU", "LLVM"}, "slow")
   def test_train_cifar(self):
diff --git a/tinygrad/ops.py b/tinygrad/ops.py
index 6bcdf13a62..f53f15626a 100644
--- a/tinygrad/ops.py
+++ b/tinygrad/ops.py
@@ -212,7 +212,7 @@ class UOpMetaClass(type):
     return created
 
 # some uops map to other stuff
-buffers:weakref.WeakKeyDictionary[UOp, Buffer] = weakref.WeakKeyDictionary() # this maps BUFFER uops to their device Buffers
+buffers:Dict[UOp, weakref.ReferenceType[Buffer]] = {} # this maps BUFFER uops to their device Buffers
 realized:weakref.WeakKeyDictionary[UOp, UOp] = weakref.WeakKeyDictionary() # this maps realized ops to a BUFFER uop
 forced_realize:weakref.WeakSet[UOp] = weakref.WeakSet()
 
@@ -223,9 +223,7 @@ class UOp(MathTrait, metaclass=UOpMetaClass):
   dtype:DType = dtypes.void
   src:Tuple[UOp, ...] = tuple()
   arg:Any = None
-  def __del__(self):
-    if self.op is Ops.BUFFER: self.buffer.ref(-1)
-    del UOpMetaClass.ucache[(self.op, self.dtype, self.src, self.arg)]
+  def __del__(self): del UOpMetaClass.ucache[(self.op, self.dtype, self.src, self.arg)]
   def __reduce__(self): return UOp, (self.op, self.dtype, self.src, self.arg)
   def replace(self, **kwargs) -> UOp:
     new_args = (kwargs.pop("op", self.op), kwargs.pop("dtype", self.dtype), kwargs.pop("src", self.src), kwargs.pop("arg", self.arg))
@@ -440,14 +438,14 @@ class UOp(MathTrait, metaclass=UOpMetaClass):
   @property
   def buffer(self) -> Buffer:
     if self.base.realized is not None: return self.base.realized
-    if (ret:=buffers.get(self)) is not None: return ret
+    if (wret:=buffers.get(self)) is not None and (ret:=wret()) is not None: return ret
     if self.op is Ops.VIEW:
       assert unwrap(self.st).contiguous, "VIEW only works here if it's contiguous"
       return self.src[0].buffer
     assert self.op is Ops.BUFFER, f"must be BUFFER {self.op}"
     from tinygrad.device import Buffer
-    buffers[self] = ret = Buffer(*self.arg[1])
-    return ret
+    buffers[self] = weakref.ref(created:=Buffer(*self.arg[1]))
+    return created
   @property
   def realized(self) -> Optional[Buffer]: return real_buf_uop.buffer if (real_buf_uop:=realized.get(self)) is not None else None
   @property