diff --git a/options_go1.7.go b/options_go1.7.go
index 2b5f67b..a3cddab 100644
--- a/options_go1.7.go
+++ b/options_go1.7.go
@@ -1,3 +1,5 @@
+//+build go1.7
+
 package mpb
 
 import "context"