Feature For Multiple OS - tycho

Question

I want to create a feature for the basic Eclipse platform used to create our applications, but for multiple operating systems.
Since the feature.xml seems to support it, I thought as was easy as doing something like this:
<plugin
id="org.eclipse.swt"
download-size="0"
install-size="0"
version="0.0.0"
unpack="false"/>
<plugin
id="org.eclipse.swt.win32.win32.x86"
os="win32"
ws="win32"
arch="x86"
download-size="0"
install-size="0"
version="0.0.0"
fragment="true"
unpack="false"/>
<plugin
id="org.eclipse.swt.win32.win32.x86_64"
os="win32"
ws="win32"
arch="x86_64"
download-size="0"
install-size="0"
version="0.0.0"
fragment="true"
unpack="false"/>
...adding the plug-ins into a target platform and building it using Tycho. However I get the following exception:
[ERROR] Cannot resolve target definition:
[ERROR] Problems resolving provisioning plan.:
[ERROR] org.eclipse.swt.win32.win32.x86_64 3.7.2.v3740f cannot be installed in this environment because its filter is not applicable.
[ERROR]
[ERROR] Failed to resolve target definition C:\workspaces\MyGreatWorkspace\org.acme.platform.feature\build.target: See log for details: org.eclipse.swt.win32.win32.x86_64 3.7.2.v3740f cannot be installed in this environment because its filter is not applicable. -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
Neither the target platform definition nor the pom.xml have defined the environment tag, so I'm not even sure what Tycho is validating against.
Having the environment tag doesn't change the exception either:
<plugin>
<groupId>org.eclipse.tycho</groupId>
<artifactId>target-platform-configuration</artifactId>
<configuration>
<!-- [SNIP] -->
<environments>
<environment>
<os>win32</os>
<ws>win32</ws>
<arch>x86</arch>
</environment>
<environment>
<os>win32</os>
<ws>win32</ws>
<arch>x86_64</arch>
</environment>
</environments>
</configuration>
How do I create a feature for multiple operating systems?