diff --git a/Include/pythonrun.h b/Include/pythonrun.h
index 09d3b57..7d4f056 100644
--- a/Include/pythonrun.h
+++ b/Include/pythonrun.h
@@ -42,6 +42,7 @@
 
 void Py_Initialize Py_PROTO((void));
 void Py_Finalize Py_PROTO((void));
+int Py_IsInitialized Py_PROTO((void));
 PyThreadState *Py_NewInterpreter Py_PROTO((void));
 void Py_EndInterpreter Py_PROTO((PyThreadState *));