diff --git a/mypy/main.py b/mypy/main.py
index 4d9cec63bbc19..9ea189f675ebc 100644
--- a/mypy/main.py
+++ b/mypy/main.py
@@ -1449,9 +1449,7 @@ def set_strict_flags() -> None:
         process_cache_map(parser, special_opts, options)
 
     # Process --strict-bytes
-    if options.strict_bytes:
-        options.disable_bytearray_promotion = True
-        options.disable_memoryview_promotion = True
+    options.process_strict_bytes()
 
     # An explicitly specified cache_fine_grained implies local_partial_types
     # (because otherwise the cache is not compatible with dmypy)
diff --git a/mypy/options.py b/mypy/options.py
index c086dfc8aea36..52afd27211ed0 100644
--- a/mypy/options.py
+++ b/mypy/options.py
@@ -466,6 +466,16 @@ def process_incomplete_features(
             if feature in COMPLETE_FEATURES:
                 warning_callback(f"Warning: {feature} is already enabled by default")
 
+    def process_strict_bytes(self) -> None:
+        # Sync `--strict-bytes` and `--disable-{bytearray,memoryview}-promotion`
+        if self.strict_bytes:
+            # backwards compatibility
+            self.disable_bytearray_promotion = True
+            self.disable_memoryview_promotion = True
+        elif self.disable_bytearray_promotion and self.disable_memoryview_promotion:
+            # forwards compatibility
+            self.strict_bytes = True
+
     def apply_changes(self, changes: dict[str, object]) -> Options:
         # Note: effects of this method *must* be idempotent.
         new_options = Options()
diff --git a/mypy/stubtest.py b/mypy/stubtest.py
index ab29d9dca4b83..6c90913885c93 100644
--- a/mypy/stubtest.py
+++ b/mypy/stubtest.py
@@ -2003,6 +2003,7 @@ def warning_callback(msg: str) -> None:
     options.process_incomplete_features(
         error_callback=error_callback, warning_callback=warning_callback
     )
+    options.process_strict_bytes()
 
     try:
         modules = build_stubs(modules, options, find_submodules=not args.check_typeshed)