diff --git a/examples/trees/cart.go b/examples/trees/cart.go
index 22d3763..5a19cab 100644
--- a/examples/trees/cart.go
+++ b/examples/trees/cart.go
@@ -6,6 +6,8 @@ import (
 	"fmt"
 
 	"github.com/sjwhitworth/golearn/base"
+	"github.com/sjwhitworth/golearn/trees"
+
 )
 
 func main() {