diff --git a/WORKSPACE b/WORKSPACE
index ed0f3bd..eb8a13c 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -14,9 +14,9 @@
 
 http_archive(
     name = "io_bazel_rules_closure",
-    sha256 = "4f2c173ebf95e94d98a0d5cb799e734536eaf3eca280eb15e124f5e5ef8b6e39",
-    strip_prefix = "rules_closure-6fd76e645b5c622221c9920f41a4d0bc578a3046",
-    urls = ["https://github.com/bazelbuild/rules_closure/archive/6fd76e645b5c622221c9920f41a4d0bc578a3046.tar.gz"],
+    sha256 = "0e6de40666f2ebb2b30dc0339745a274d9999334a249b05a3b1f46462e489adf",
+    strip_prefix = "rules_closure-87d24b1df8b62405de8dd059cb604fd9d4b1e395",
+    urls = ["https://github.com/bazelbuild/rules_closure/archive/87d24b1df8b62405de8dd059cb604fd9d4b1e395.tar.gz"],
 )
 
 # File is specific to Polymer and copied from the Closure Github -- should be
diff --git a/tools/bzl/classpath.bzl b/tools/bzl/classpath.bzl
index 9ec5f15..55479c5 100644
--- a/tools/bzl/classpath.bzl
+++ b/tools/bzl/classpath.bzl
@@ -1,13 +1,13 @@
 def _classpath_collector(ctx):
-    all = depset()
+    all = []
     for d in ctx.attr.deps:
         if hasattr(d, "java"):
-            all += d.java.transitive_runtime_deps
-            all += d.java.compilation_info.runtime_classpath
+            all.append(d.java.transitive_runtime_deps)
+            all.append(d.java.compilation_info.runtime_classpath)
         elif hasattr(d, "files"):
-            all += d.files
+            all.append(d.files)
 
-    as_strs = [c.path for c in all.to_list()]
+    as_strs = [c.path for c in depset(transitive = all).to_list()]
     ctx.actions.write(
         output = ctx.outputs.runtime,
         content = "\n".join(sorted(as_strs)),
diff --git a/tools/bzl/gwt.bzl b/tools/bzl/gwt.bzl
index 91385dd..234d320 100644
--- a/tools/bzl/gwt.bzl
+++ b/tools/bzl/gwt.bzl
@@ -196,17 +196,17 @@
     )
 
 def _get_transitive_closure(ctx):
-    deps = depset()
+    deps = []
     for dep in ctx.attr.module_deps:
-        deps += dep.java.transitive_runtime_deps
-        deps += dep.java.transitive_source_jars
+        deps.append(dep.java.transitive_runtime_deps)
+        deps.append(dep.java.transitive_source_jars)
     for dep in ctx.attr.deps:
         if hasattr(dep, "java"):
-            deps += dep.java.transitive_runtime_deps
+            deps.append(dep.java.transitive_runtime_deps)
         elif hasattr(dep, "files"):
-            deps += dep.files
+            deps.append(dep.files)
 
-    return deps
+    return depset(transitive = deps)
 
 gwt_binary = rule(
     attrs = {
diff --git a/tools/bzl/javadoc.bzl b/tools/bzl/javadoc.bzl
index d315f8f..fcf9f33 100644
--- a/tools/bzl/javadoc.bzl
+++ b/tools/bzl/javadoc.bzl
@@ -17,13 +17,10 @@
 def _impl(ctx):
     zip_output = ctx.outputs.zip
 
-    transitive_jar_set = depset()
-    source_jars = depset()
-    for l in ctx.attr.libs:
-        source_jars += l.java.source_jars
-        transitive_jar_set += l.java.transitive_deps
+    transitive_jars = depset(transitive = [l.java.transitive_deps for l in ctx.attr.libs])
+    source_jars = depset(transitive = [l.java.source_jars for l in ctx.attr.libs])
 
-    transitive_jar_paths = [j.path for j in transitive_jar_set.to_list()]
+    transitive_jar_paths = [j.path for j in transitive_jars.to_list()]
     dir = ctx.outputs.zip.path + ".dir"
     source = ctx.outputs.zip.path + ".source"
     external_docs = ["http://docs.oracle.com/javase/8/docs/api"] + ctx.attr.external_docs
@@ -56,7 +53,7 @@
         "(cd %s && zip -Xqr ../%s *)" % (dir, ctx.outputs.zip.basename),
     ]
     ctx.actions.run_shell(
-        inputs = transitive_jar_set.to_list() + source_jars.to_list() + ctx.files._jdk,
+        inputs = transitive_jars.to_list() + source_jars.to_list() + ctx.files._jdk,
         outputs = [zip_output],
         command = " && ".join(cmd),
     )
diff --git a/tools/bzl/js.bzl b/tools/bzl/js.bzl
index a4f43fe..4061a77 100644
--- a/tools/bzl/js.bzl
+++ b/tools/bzl/js.bzl
@@ -130,20 +130,20 @@
 )
 
 def _bower_component_impl(ctx):
-    transitive_zipfiles = depset([ctx.file.zipfile])
-    for d in ctx.attr.deps:
-        transitive_zipfiles += d.transitive_zipfiles
+    transitive_zipfiles = depset(
+        direct = [ctx.file.zipfile],
+        transitive = [d.transitive_zipfiles for d in ctx.attr.deps],
+    )
 
-    transitive_licenses = depset()
-    if ctx.file.license:
-        transitive_licenses += depset([ctx.file.license])
+    transitive_licenses = depset(
+        direct = [ctx.file.license],
+        transitive = [d.transitive_licenses for d in ctx.attr.deps],
+    )
 
-    for d in ctx.attr.deps:
-        transitive_licenses += d.transitive_licenses
-
-    transitive_versions = depset(ctx.files.version_json)
-    for d in ctx.attr.deps:
-        transitive_versions += d.transitive_versions
+    transitive_versions = depset(
+        direct = ctx.files.version_json,
+        transitive = [d.transitive_versions for d in ctx.attr.deps],
+    )
 
     return struct(
         transitive_zipfiles = transitive_zipfiles,
@@ -182,14 +182,14 @@
         mnemonic = "GenBowerZip",
     )
 
-    licenses = depset()
+    licenses = []
     if ctx.file.license:
-        licenses += depset([ctx.file.license])
+        licenses.append(ctx.file.license)
 
     return struct(
         transitive_zipfiles = list([ctx.outputs.zip]),
         transitive_versions = depset(),
-        transitive_licenses = licenses,
+        transitive_licenses = depset(licenses),
     )
 
 js_component = rule(
@@ -232,15 +232,16 @@
     """A bunch of bower components zipped up."""
     zips = depset()
     for d in ctx.attr.deps:
-        zips += d.transitive_zipfiles
+        files = d.transitive_zipfiles
 
-    versions = depset()
-    for d in ctx.attr.deps:
-        versions += d.transitive_versions
+        # TODO(davido): Make sure the field always contains a depset
+        if type(files) == "list":
+            files = depset(files)
+        zips = depset(transitive = [zips, files])
 
-    licenses = depset()
-    for d in ctx.attr.deps:
-        licenses += d.transitive_versions
+    versions = depset(transitive = [d.transitive_versions for d in ctx.attr.deps])
+
+    licenses = depset(transitive = [d.transitive_versions for d in ctx.attr.deps])
 
     out_zip = ctx.outputs.zip
     out_versions = ctx.outputs.version_json
diff --git a/tools/bzl/pkg_war.bzl b/tools/bzl/pkg_war.bzl
index 1142a55..5c07987 100644
--- a/tools/bzl/pkg_war.bzl
+++ b/tools/bzl/pkg_war.bzl
@@ -75,35 +75,39 @@
     ]
 
     # Add lib
-    transitive_lib_deps = depset()
+    transitive_libs = []
     for l in ctx.attr.libs:
         if hasattr(l, "java"):
-            transitive_lib_deps += l.java.transitive_runtime_deps
+            transitive_libs.append(l.java.transitive_runtime_deps)
         elif hasattr(l, "files"):
-            transitive_lib_deps += l.files
+            transitive_libs.append(l.files)
 
+    transitive_lib_deps = depset(transitive = transitive_libs)
     for dep in transitive_lib_deps.to_list():
         cmd += _add_file(dep, build_output + "/WEB-INF/lib/")
         inputs.append(dep)
 
     # Add pgm lib
-    transitive_pgmlib_deps = depset()
+    transitive_pgmlibs = []
     for l in ctx.attr.pgmlibs:
-        transitive_pgmlib_deps += l.java.transitive_runtime_deps
+        transitive_pgmlibs.append(l.java.transitive_runtime_deps)
 
+    transitive_pgmlib_deps = depset(transitive = transitive_pgmlibs)
     for dep in transitive_pgmlib_deps.to_list():
         if dep not in inputs:
             cmd += _add_file(dep, build_output + "/WEB-INF/pgm-lib/")
             inputs.append(dep)
 
     # Add context
-    transitive_context_deps = depset()
+    transitive_context_libs = []
     if ctx.attr.context:
         for jar in ctx.attr.context:
             if hasattr(jar, "java"):
-                transitive_context_deps += jar.java.transitive_runtime_deps
+                transitive_context_libs.append(jar.java.transitive_runtime_deps)
             elif hasattr(jar, "files"):
-                transitive_context_deps += jar.files
+                transitive_context_libs.append(jar.files)
+
+    transitive_context_deps = depset(transitive = transitive_context_libs)
     for dep in transitive_context_deps.to_list():
         cmd += _add_context(dep, build_output)
         inputs.append(dep)