diff --git a/mibuild/altera_quartus.py b/mibuild/altera_quartus.py
index 0973545be..781b104ff 100644
--- a/mibuild/altera_quartus.py
+++ b/mibuild/altera_quartus.py
@@ -3,6 +3,7 @@
 
 import os, subprocess
 
+from migen.fhdl.structure import _Fragment
 from mibuild.generic_platform import *
 from mibuild.crg import SimpleCRG
 from mibuild import tools