diff --git a/techlibs/coolrunner2/synth_coolrunner2.cc b/techlibs/coolrunner2/synth_coolrunner2.cc
index 562cce460..183282629 100644
--- a/techlibs/coolrunner2/synth_coolrunner2.cc
+++ b/techlibs/coolrunner2/synth_coolrunner2.cc
@@ -164,6 +164,8 @@ struct SynthCoolrunner2Pass : public ScriptPass
 			run("dffinit -ff LDCP_N Q INIT");
 			run("coolrunner2_sop");
 			run("iopadmap -bits -inpad IBUF O:I -outpad IOBUFE I:IO -inoutpad IOBUFE O:IO -toutpad IOBUFE E:I:IO -tinoutpad IOBUFE E:O:I:IO");
+			run("attrmvcp -attr src -attr LOC t:IOBUFE n:*");
+			run("attrmvcp -attr src -attr LOC -driven t:IBUF n:*");
 			run("clean");
 		}