.

bigfile/_bigfile.c

@@ -926,10 +926,9 @@ pyfileh_open(PyObject *pyfile0, PyObject *args)
 
     if (mmap_overlay == -1)
         mmap_overlay = (pyfile->blkmmap_ops != NULL ? 1 : 0);
-    if (mmap_overlay && pyfile->blkmmap_ops == NULL) {
-        PyErr_SetString(PyExc_TypeError, "BigFile subtype does not provide blkmmapper");
-        return NULL;
-    }
+    if (mmap_overlay && pyfile->blkmmap_ops == NULL)
+        return PyErr_Format(PyExc_TypeError,
+                "%s type does not provide blkmmapper", pyfile0->ob_type->tp_name);
 
     pyfileh = PyType_New(PyBigFileH, &PyBigFileH_Type, NULL);
     if (!pyfileh)