diff --git a/extra/sqtt/test_timing.py b/extra/sqtt/test_timing.py
index f412ceda3e..e9a16c6a35 100644
--- a/extra/sqtt/test_timing.py
+++ b/extra/sqtt/test_timing.py
@@ -18,15 +18,17 @@ from extra.sqtt.roc import decode, InstExec, PrgExec
 
 dev = Device["AMD"]
 
+def custom(arg:str, s:UOp|None=None) -> UOp: return UOp(Ops.CUSTOM, src=(s,) if s is not None else (), arg=arg)
+
 def asm_kernel(instrs:list[str], l:int=1, g:int=1) -> Tensor:
   name = sys._getframe(1).f_code.co_name
   def fxn(_):
     L = UOp.special(l, "lidx0")
     G = UOp.special(g, "gidx0")
-    ops:list[str] = [UOp(Ops.CUSTOM, arg="asm volatile (")]
-    for inst in instrs: ops.append(UOp(Ops.CUSTOM, src=(ops[-1],), arg=f'  "{inst}\\n\\t"'))
-    ops.append(UOp(Ops.CUSTOM, src=(ops[-1],), arg=");"))
-    return UOp.sink(*ops, L, G, arg=KernelInfo(name=name))
+    op = custom("asm volatile (")
+    for inst in instrs: op = custom(f'  "{inst}\\n\\t"', op)
+    op = custom(");", op)
+    return UOp.sink(op, L, G, arg=KernelInfo(name=name))
   k = Tensor.custom_kernel(Tensor.empty(1), fxn=fxn)[0]
   return k
 
@@ -87,12 +89,11 @@ class TestTiming(unittest.TestCase):
     n = 1
     def sleep_kernel(data0):
       assert data0.dtype.base == dtypes.ulong
-      ops:list[UOp] = []
-      ops.append(UOp(Ops.CUSTOM, arg="unsigned long long t0 = __builtin_readcyclecounter();"))
-      ops.append(UOp(Ops.CUSTOM, arg=f"__builtin_amdgcn_s_sleep({n});", src=(ops[-1],)))
-      ops.append(UOp(Ops.CUSTOM, arg="unsigned long long t1 = __builtin_readcyclecounter();", src=(ops[-1],)))
-      ops.append(UOp(Ops.CUSTOM, arg=f"data0_{data0.size}[0] = t1 - t0;", src=(ops[-1],)))
-      return UOp.sink(data0, *ops, arg=KernelInfo(name=f"sleep_{n}"))
+      op = custom("unsigned long long t0 = __builtin_readcyclecounter();")
+      op = custom(f"__builtin_amdgcn_s_sleep({n});", op)
+      op = custom(f"unsigned long long t1 = __builtin_readcyclecounter();", op)
+      op = custom(f"data0_{data0.size}[0] = t1 - t0;", op)
+      return UOp.sink(data0, op, arg=KernelInfo(name=f"sleep_{n}"))
     diff_hw_reg = Tensor.empty(1, dtype=dtypes.ulong)
     diff_hw_reg = Tensor.custom_kernel(diff_hw_reg, fxn=sleep_kernel)[0]
     with save_sqtt() as sqtt: