diff --git a/Include/pystate.h b/Include/pystate.h
index f6a26fd..e578024 100644
--- a/Include/pystate.h
+++ b/Include/pystate.h
@@ -104,7 +104,7 @@
 
 /* Variable and macro for in-line access to current thread state */
 
-DL_IMPORT(PyThreadState *) _PyThreadState_Current;
+extern DL_IMPORT(PyThreadState *) _PyThreadState_Current;
 
 #ifdef Py_DEBUG
 #define PyThreadState_GET() PyThreadState_Get()