diff --git a/src/pkg/runtime/iface.goc b/src/pkg/runtime/iface.goc
index 08da8c7337..96bb8b8aa4 100644
--- a/src/pkg/runtime/iface.goc
+++ b/src/pkg/runtime/iface.goc
@@ -161,7 +161,7 @@ copyin(Type *t, void *src, void **dst)
 	if(size <= sizeof(*dst))
 		alg->copy(size, dst, src);
 	else {
-		p = runtime·mal(size);
+		p = runtime·cnew(t);
 		alg->copy(size, p, src);
 		*dst = p;
 	}