diff --git a/mypy/bogus_type.py b/mypy/bogus_type.py
index 835c99bea397..fcf8accd0794 100644
--- a/mypy/bogus_type.py
+++ b/mypy/bogus_type.py
@@ -19,7 +19,8 @@
 
 # This won't ever be true at runtime, but we consider it true during
 # mypyc compilations.
-if sys.platform == 'mypyc':
+MYPYC = False
+if MYPYC:
     Bogus = FlexibleAlias[T, Any]
 else:
     Bogus = FlexibleAlias[T, T]
diff --git a/mypy_bootstrap.ini b/mypy_bootstrap.ini
index 1c4f8a1a8cf4..3a6eee6449d2 100644
--- a/mypy_bootstrap.ini
+++ b/mypy_bootstrap.ini
@@ -12,5 +12,4 @@ disallow_any_unimported = True
 warn_redundant_casts = True
 warn_unused_configs = True
 show_traceback = True
-# Set the platform to something nonsense to signal to make Bogus = Any.
-platform = mypyc
+always_true = MYPYC
diff --git a/mypy_self_check.ini b/mypy_self_check.ini
index c865d538bac6..fcc26f49a4b6 100644
--- a/mypy_self_check.ini
+++ b/mypy_self_check.ini
@@ -12,3 +12,4 @@ disallow_any_unimported = True
 warn_redundant_casts = True
 warn_unused_configs = True
 show_traceback = True
+always_false = MYPYC