diff --git a/WORKSPACE b/WORKSPACE
index eae8af41c..4195d2a86 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -73,12 +73,9 @@ http_archive(
 http_archive(
     name = "zlib",
     build_file = "@//third_party:zlib.BUILD",
-    sha256 = "c3e5e9fdd5004dcb542feda5ee4f0ff0744628baf8ed2dd5d66f8ca1197cb1a1",
-    strip_prefix = "zlib-1.2.11",
-    urls = [
-        "http://mirror.bazel.build/zlib.net/fossils/zlib-1.2.11.tar.gz",
-        "http://zlib.net/fossils/zlib-1.2.11.tar.gz",  # 2017-01-15
-    ],
+    sha256 = "b3a24de97a8fdbc835b9833169501030b8977031bcb54b3b3ac13740f846ab30",
+    strip_prefix = "zlib-1.2.13",
+    url = "http://zlib.net/fossils/zlib-1.2.13.tar.gz",
     patches = [
         "@//third_party:zlib.diff",
     ],