diff --git a/grpc.t b/grpc.t
index e5b49ab..4a8f468 100644
--- a/grpc.t
+++ b/grpc.t
@@ -210,6 +210,8 @@
 }
 
 undef $f;
+# don't bother with a new instance until the old one is over
+select undef, undef, undef, 0.2 unless $t->has_version('1.15.4');
 $f = grpc();
 
 # various header compression formats