diff --git a/Include/structseq.h b/Include/structseq.h
index e5e5d5c..8f51c89 100644
--- a/Include/structseq.h
+++ b/Include/structseq.h
@@ -19,7 +19,7 @@
     int n_in_sequence;
 } PyStructSequence_Desc;
 
-extern char* PyStructSequence_UnnamedField;
+extern const char * const PyStructSequence_UnnamedField;
 
 #ifndef Py_LIMITED_API
 PyAPI_FUNC(void) PyStructSequence_InitType(PyTypeObject *type,