diff --git a/siso.py b/siso.py
index 8db18c5ba..a0b8902f9 100644
--- a/siso.py
+++ b/siso.py
@@ -15,29 +15,6 @@ import sys
 import gclient_paths
 
 
-def checkOutdir(args):
-    subcmd = ''
-    out_dir = "."
-    for i, arg in enumerate(ninja_args):
-        if not arg.startswith("-") and not subcmd:
-            subcmd = arg
-            continue
-        if arg == "-C":
-            out_dir = ninja_args[i + 1]
-        elif arg.startswith("-C"):
-            out_dir = arg[2:]
-    if subcmd != "ninja":
-        return
-    ninja_marker = os.path.join(out_dir, ".ninja_deps")
-    if os.path.exists(ninja_marker):
-        print("depot_tools/siso.py: %s contains Ninja state file.\n"
-              "Use `autoninja` to use reclient,\n"
-              "or run `gn clean %s` to switch from ninja to siso\n" %
-              (out_dir, out_dir),
-              file=sys.stderr)
-        sys.exit(1)
-
-
 def main(args):
     # Propagate signals to siso process so that it can run cleanup steps.
     # Siso will be terminated immediately after the second Ctrl-C.
@@ -101,7 +78,6 @@ def main(args):
             base_path, 'third_party', 'siso',
             'siso' + gclient_paths.GetExeSuffix())
         if os.path.isfile(siso_path):
-            checkOutdir(args[1:])
             return subprocess.call([siso_path] + args[1:], env=env)
 
     print(