diff --git a/subpar.bzl b/subpar.bzl
index 9134b84..f12230d 100644
--- a/subpar.bzl
+++ b/subpar.bzl
@@ -189,7 +189,7 @@ def par_binary(name, **kwargs):
     See [py_binary](http://www.bazel.io/docs/be/python.html#py_binary)
     for arguments and usage.
     """
-    compiler = kwargs.pop('compiler', DEFAULT_COMPILER)
+    compiler = kwargs.pop('compiler', None)
     zip_safe = kwargs.pop('zip_safe', True)
     native.py_binary(name=name, **kwargs)
 
@@ -216,7 +216,7 @@ def par_test(name, **kwargs):
     Just like par_binary, but for py_test instead of py_binary.  Useful if you
     specifically need to test a module's behaviour when used in a .par binary.
     """
-    compiler = kwargs.pop('compiler', DEFAULT_COMPILER)
+    compiler = kwargs.pop('compiler', None)
     zip_safe = kwargs.pop('zip_safe', True)
     native.py_test(name=name, **kwargs)
 
diff --git a/tests/BUILD b/tests/BUILD
index 43a602c..a87f306 100644
--- a/tests/BUILD
+++ b/tests/BUILD
@@ -184,3 +184,12 @@ par_binary(
     ("shadow", "//tests:package_shadow/main", "tests/package_shadow/main"),
     ("version", "//tests:package_f/f", "tests/package_f/f"),
 ]]
+
+# Test target in external workspace
+sh_test(
+    name = "test_compiler_label_wrapper",
+    srcs = ["test_compiler_label_wrapper.sh"],
+    data = [
+        "@test_workspace//:test_compiler_label.par",
+    ],
+)
diff --git a/tests/test_compiler_label_wrapper.sh b/tests/test_compiler_label_wrapper.sh
new file mode 100755
index 0000000..5376d53
--- /dev/null
+++ b/tests/test_compiler_label_wrapper.sh
@@ -0,0 +1,8 @@
+#!/bin/sh
+
+set -eu
+
+# Did the par file compile and run?
+../test_workspace/test_compiler_label.par || exit 1
+
+echo "Pass"
diff --git a/tests/test_workspace/BUILD b/tests/test_workspace/BUILD
index 23250f7..aec5242 100644
--- a/tests/test_workspace/BUILD
+++ b/tests/test_workspace/BUILD
@@ -14,8 +14,11 @@
 
 package(default_visibility = ["//visibility:public"])
 
+load("@subpar//:subpar.bzl", "par_binary")
+
 exports_files(["data_file.txt"])
 
+# Part of the tests:external_workspace test
 py_library(
     name = "package_external_lib/external_lib",
     srcs = [
@@ -24,3 +27,11 @@ py_library(
     ],
     srcs_version = "PY2AND3",
 )
+
+# Test that we can actually compile a par_binary outside the subpar workspace.
+par_binary(
+    name = "test_compiler_label",
+    srcs = ["test_compiler_label.py"],
+    main = "test_compiler_label.py",
+    srcs_version = "PY2AND3",
+)
diff --git a/tests/test_workspace/test_compiler_label.py b/tests/test_workspace/test_compiler_label.py
new file mode 100644
index 0000000..320be4e
--- /dev/null
+++ b/tests/test_workspace/test_compiler_label.py
@@ -0,0 +1,26 @@
+# Copyright 2018 Google Inc. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Integration test program for Subpar.
+
+Test that the default `compiler` label is correctly resolved.  This
+test must be done in a workspace other than subpar's workspace.
+"""
+
+def main():
+    print('In test_compiler_label.py main()')
+
+
+if __name__ == '__main__':
+    main()