diff --git a/bind/einhorn.go b/bind/einhorn.go
index dc9aa38..d18b694 100644
--- a/bind/einhorn.go
+++ b/bind/einhorn.go
@@ -1,4 +1,4 @@
-// +build !windows !appengine
+// +build !windows,!appengine
 
 package bind
 
diff --git a/bind/systemd.go b/bind/systemd.go
index 49d0013..292f509 100644
--- a/bind/systemd.go
+++ b/bind/systemd.go
@@ -1,4 +1,4 @@
-// +build !windows !appengine
+// +build !windows,!appengine
 
 package bind
 
diff --git a/graceful/einhorn.go b/graceful/einhorn.go
index 168f5b7..ad78d1c 100644
--- a/graceful/einhorn.go
+++ b/graceful/einhorn.go
@@ -1,4 +1,4 @@
-// +build !windows !appengine
+// +build !windows,!appengine
 
 package graceful