diff --git a/Cargo.lock b/Cargo.lock
index 14afd091248..73a16a22419 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -13,6 +13,7 @@ dependencies = [
  "term 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "toml 0.1.23 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-segmentation 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "walkdir 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -145,6 +146,15 @@ name = "unicode-xid"
 version = "0.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "walkdir"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "kernel32-sys 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "winapi"
 version = "0.2.5"