diff --git a/Include/import.h b/Include/import.h
index 05ad7f0..76aecdd 100644
--- a/Include/import.h
+++ b/Include/import.h
@@ -27,6 +27,14 @@
 PyAPI_FUNC(void) PyImport_Cleanup(void);
 PyAPI_FUNC(int) PyImport_ImportFrozenModule(char *);
 
+#ifdef WITH_THREAD
+PyAPI_FUNC(void) _PyImport_AcquireLock(void);
+PyAPI_FUNC(int) _PyImport_ReleaseLock(void);
+#else
+#define _PyImport_AcquireLock()
+#define _PyImport_ReleaseLock() 1
+#endif
+
 PyAPI_FUNC(struct filedescr *) _PyImport_FindModule(
 	const char *, PyObject *, char *, size_t, FILE **, PyObject **);
 PyAPI_FUNC(int) _PyImport_IsScript(struct filedescr *);