diff --git a/tinygrad/codegen/uops.py b/tinygrad/codegen/uops.py
index d11b2da115..d9971f1c8e 100644
--- a/tinygrad/codegen/uops.py
+++ b/tinygrad/codegen/uops.py
@@ -27,7 +27,7 @@ class UOps(Enum):
   ENDRANGE = auto(); ENDIF = auto() # noqa: E702
 
 def ufix(dtype: Optional[DType], x): return UOp.const(dtype, x) if not isinstance(x, UOp) else x
-@dataclass(eq=False)
+@dataclass(frozen=True, eq=False)
 class UOp:
   op: UOps
   dtype: Optional[DType] = None
@@ -313,7 +313,7 @@ class UOpGraph:
     run_cnt = 0
     while changed:
       changed = 0
-      @functools.lru_cache
+      @functools.lru_cache(None)
       def rewrite(u:UOp) -> UOp:
         nonlocal changed
         recurse_cnt = 0
@@ -324,12 +324,8 @@ class UOpGraph:
           up = rewritten
           recurse_cnt += 1
         changed += recurse_cnt
-        # NOTE: this changes UOp, so we have to delete caches
-        up.src = tuple(rewrite(x) for x in up.src)
-        if 'parents' in up.__dict__: delattr(up, 'parents')
-        if 'cmp_tuple' in up.__dict__: delattr(up, 'cmp_tuple')
-        # replace with cached nodes
-        return self.nodes.setdefault(up.tuple(), up)
+        up = UOp(up.op, up.dtype, tuple(rewrite(x) for x in up.src), up.arg)
+        return self.nodes.setdefault(up.tuple(), up) # replace with cached nodes
       sink = rewrite(sink)
       run_cnt += 1
       assert run_cnt < 100, "exceeded 100 rewrite loops!"