diff --git a/Include/fileobject.h b/Include/fileobject.h
index ebbb521..9fd0646 100644
--- a/Include/fileobject.h
+++ b/Include/fileobject.h
@@ -57,6 +57,11 @@
 char *Py_UniversalNewlineFgets(char *, int, FILE*, PyObject *);
 size_t Py_UniversalNewlineFread(char *, size_t, FILE *, PyObject *);
 
+/* A routine to do sanity checking on the file mode string.  returns
+   non-zero on if an exception occurred
+*/
+int _PyFile_SanitizeMode(char *mode);
+
 #ifdef __cplusplus
 }
 #endif