diff --git a/src/Cargo.lock b/src/Cargo.lock
index 45396a45a4c..e9a20a7c79c 100644
--- a/src/Cargo.lock
+++ b/src/Cargo.lock
@@ -1554,7 +1554,6 @@ dependencies = [
  "ar 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "arena 0.0.0",
  "env_logger 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "flate2 0.2.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "graphviz 0.0.0",
  "log 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "owning_ref 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/src/librustc_driver/Cargo.toml b/src/librustc_driver/Cargo.toml
index 2aac1b085e9..d6155f53485 100644
--- a/src/librustc_driver/Cargo.toml
+++ b/src/librustc_driver/Cargo.toml
@@ -10,7 +10,6 @@ crate-type = ["dylib"]
 
 [dependencies]
 arena = { path = "../libarena" }
-flate2 = "0.2"
 graphviz = { path = "../libgraphviz" }
 log = { version = "0.3", features = ["release_max_level_info"] }
 owning_ref = "0.3.3"