diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index dee4965..c33457f 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1100,6 +1100,7 @@
 	{"no_user_site",	"-s"},
 	{"no_site",		"-S"},
 	{"ignore_environment",	"-E"},
+	{"tabcheck",		"-t or -tt"},
 	{"verbose",		"-v"},
 #ifdef RISCOS
 	{"riscos_wimp",		"???"},
@@ -1115,9 +1116,9 @@
 	flags__doc__,	/* doc */
 	flags_fields,	/* fields */
 #ifdef RISCOS
-	11
+	12
 #else
-	10
+	11
 #endif
 };
 
@@ -1143,6 +1144,7 @@
 	SetFlag(Py_NoUserSiteDirectory);
 	SetFlag(Py_NoSiteFlag);
 	SetFlag(Py_IgnoreEnvironmentFlag);
+	SetFlag(Py_TabcheckFlag);
 	SetFlag(Py_VerboseFlag);
 #ifdef RISCOS
 	SetFlag(Py_RISCOSWimpFlag);