diff --git a/common/nextpnr.h b/common/nextpnr.h
index e52f72c2..1cf0cbbb 100644
--- a/common/nextpnr.h
+++ b/common/nextpnr.h
@@ -208,7 +208,7 @@ struct PortRef
 {
     CellInfo *cell = nullptr;
     IdString port;
-    delay_t budget;
+    delay_t budget = 0;
 };
 
 struct NetInfo