fix missing import
diff --git a/clientconn.go b/clientconn.go
index 4eec42b..30d8d7b 100644
--- a/clientconn.go
+++ b/clientconn.go
@@ -40,6 +40,7 @@
 	"net"
 	"sync"
 	"time"
+	"strings"
 
 	"golang.org/x/net/context"
 	"golang.org/x/net/trace"