diff --git a/tools/tools.go b/tools/tools.go
index b7d2bda14..8537476f0 100644
--- a/tools/tools.go
+++ b/tools/tools.go
@@ -1,3 +1,5 @@
+// +build tools
+
 // package tool pins a number of Go dependencies that we use. Go builds really fast,
 // so wherever we can, we just build from source rather than pulling in third party binaries.
 package main