diff --git a/tools/clean-repos/main.go b/tools/clean-repos/main.go
new file mode 100644
index 0000000..235ca9e
--- /dev/null
+++ b/tools/clean-repos/main.go
@@ -0,0 +1,31 @@
+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"os"
+	"time"
+)
+
+func main() {
+	files, err := ioutil.ReadDir("_repos/src")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	for _, f := range files {
+		if f.IsDir() {
+			dirs, err := ioutil.ReadDir("_repos/src/" + f.Name())
+			if err != nil {
+				log.Fatal(err)
+			}
+			for _, d := range dirs {
+				if time.Now().Sub(d.ModTime()) > 30*24*time.Hour {
+					path := "_repos/src/" + f.Name() + "/" + d.Name()
+					log.Printf("Deleting %s...", path)
+					os.RemoveAll(path)
+				}
+			}
+		}
+	}
+}