diff --git a/README.md b/README.md
index 932f05bb..5e6eb012 100644
--- a/README.md
+++ b/README.md
@@ -44,7 +44,7 @@ Usage
         - os: osx
 
     script:
-      - pip install cibuildwheel==0.4.0
+      - pip install cibuildwheel==0.4.1
       - cibuildwheel --output-dir wheelhouse
     ```
 
@@ -54,7 +54,7 @@ Usage
 
     ```
     build_script:
-      - pip install cibuildwheel==0.4.0
+      - pip install cibuildwheel==0.4.1
       - cibuildwheel --output-dir wheelhouse
     artifacts:
       - path: "wheelhouse\\*.whl"
@@ -235,6 +235,7 @@ Working examples
 Here are some repos that use cibuildwheel. 
 
 - [pyinstrument_cext](https://github.com/joerick/pyinstrument_cext)
+- [websockets](https://github.com/aaugustin/websockets)
 
 > Add repo here! Send a PR.
 
@@ -246,6 +247,11 @@ Since `cibuildwheel` runs the wheel through delocate or auditwheel, it will auto
 Changelog
 =========
 
+### 0.4.1
+
+- Fixed a bug on Windows where subprocess' output was hidden (#23)
+- Fixed a bug on Appveyor where logs would appear in the wrong order due to output buffering (#24, thanks @YannickJadoul!)
+
 ### 0.4.0
 
 - Fixed a bug that was increasing the build time by building the wheel twice. This was a problem for large projects that have a long build time. If you're upgrading and you need the old behaviour, use `CIBW_BEFORE_BUILD={pip} install .`, or install exactly the dependencies you need in `CIBW_BEFORE_BUILD`. See #18.
diff --git a/appveyor.yml b/appveyor.yml
index e75f0975..c96d6e2e 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -1,3 +1,5 @@
 build_script:
   - pip install -r requirements-dev.txt
-  - python ./bin/run_tests.py
+  # the '-u' flag is required so the output is in the correct order. 
+  # See https://github.com/joerick/cibuildwheel/pull/24 for more info.
+  - python -u ./bin/run_tests.py
diff --git a/cibuildwheel/__init__.py b/cibuildwheel/__init__.py
index abeeedbf..f0ede3d3 100644
--- a/cibuildwheel/__init__.py
+++ b/cibuildwheel/__init__.py
@@ -1 +1 @@
-__version__ = '0.4.0'
+__version__ = '0.4.1'
diff --git a/cibuildwheel/windows.py b/cibuildwheel/windows.py
index 1c7afe38..d44125f1 100644
--- a/cibuildwheel/windows.py
+++ b/cibuildwheel/windows.py
@@ -11,6 +11,10 @@ from .util import prepare_command
 
 
 def build(project_dir, package_name, output_dir, test_command, test_requires, before_build, skip, environment):
+    # Python under AppVeyor/Windows seems to be buffering by default, giving problems interleaving subprocess call output with unflushed calls to 'print'
+    sys.stdout.flush()
+    sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)
+
     # run_with_env is a cmd file that sets the right environment variables to
     run_with_env = os.path.join(tempfile.gettempdir(), 'appveyor_run_with_env.cmd')
     if not os.path.exists(run_with_env):
@@ -22,7 +26,7 @@ def build(project_dir, package_name, output_dir, test_command, test_requires, be
         # print the command executing for the logs
         print('+ ' + ' '.join(args))
         args = ['cmd', '/E:ON', '/V:ON', '/C', run_with_env] + args
-        return subprocess.check_output(' '.join(args), env=env, cwd=cwd)
+        return subprocess.check_call(' '.join(args), env=env, cwd=cwd)
 
     PythonConfiguration = namedtuple('PythonConfiguration', ['version', 'arch', 'identifier', 'path'])
     python_configurations = [
diff --git a/setup.cfg b/setup.cfg
index 59cb282b..85cddc12 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 0.4.0
+current_version = 0.4.1
 commit = True
 tag = True
 message = Bump version
diff --git a/setup.py b/setup.py
index 1191f54b..1ae56c9c 100644
--- a/setup.py
+++ b/setup.py
@@ -8,7 +8,7 @@ except ImportError:
 
 setup(
     name='cibuildwheel',
-    version='0.4.0',
+    version='0.4.1',
     install_requires=['bashlex'],
     description="Build Python wheels on CI with minimal configuration.",
     long_description='For readme please see http://github.com/joerick/cibuildwheel',