diff --git a/stdlib/2and3/opcode.pyi b/stdlib/2and3/opcode.pyi
index 281a6a726..b219670f5 100644
--- a/stdlib/2and3/opcode.pyi
+++ b/stdlib/2and3/opcode.pyi
@@ -17,9 +17,9 @@ HAVE_ARGUMENT: int
 EXTENDED_ARG: int
 
 if sys.version_info >= (3, 8):
-    def stack_effect(opcode: int, oparg: Optional[int] = ..., *, jump: Optional[bool] = ...) -> int: ...
+    def stack_effect(__opcode: int, __oparg: Optional[int] = ..., *, jump: Optional[bool] = ...) -> int: ...
 elif sys.version_info >= (3, 4):
-    def stack_effect(opcode: int, oparg: Optional[int] = ...) -> int: ...
+    def stack_effect(__opcode: int, __oparg: Optional[int] = ...) -> int: ...
 
 if sys.version_info >= (3, 6):
     hasnargs: List[int]
diff --git a/tests/stubtest_whitelists/py38.txt b/tests/stubtest_whitelists/py38.txt
index de0243b30..fc66969fa 100644
--- a/tests/stubtest_whitelists/py38.txt
+++ b/tests/stubtest_whitelists/py38.txt
@@ -70,7 +70,6 @@ dataclasses.field
 dataclasses.replace
 decimal.Decimal.from_float
 decimal.setcontext
-dis.stack_effect
 email.message.MIMEPart.as_string
 enum.Enum._generate_next_value_
 functools.partialmethod.__get__
@@ -101,7 +100,6 @@ multiprocessing.pool.CLOSE
 multiprocessing.pool.RUN
 multiprocessing.pool.TERMINATE
 multiprocessing.spawn._main
-opcode.stack_effect
 os.MFD_HUGE_32MB
 os.MFD_HUGE_512MB
 os.pipe2