diff --git a/shlax/actions/packages.py b/shlax/actions/packages.py
index 37f6d4b..e9f0497 100644
--- a/shlax/actions/packages.py
+++ b/shlax/actions/packages.py
@@ -141,7 +141,7 @@ class Packages(Action):
         cachedir = os.path.join(self.cache_root, self.mgr)
         await self.mount(cachedir, '/var/cache/apk')
         # special step to enable apk cache
-        await self.rexec('ln -s /var/cache/apk /etc/apk/cache')
+        await self.rexec('ln -sf /var/cache/apk /etc/apk/cache')
         return cachedir
 
     async def dnf_setup(self):
diff --git a/shlaxfile.py b/shlaxfile.py
index 9a8d576..ec57e48 100755
--- a/shlaxfile.py
+++ b/shlaxfile.py
@@ -4,6 +4,7 @@ from shlax.contrib.gitlab import *
 PYTEST = 'py.test -svv tests'
 
 build = Buildah(
+    Packages('py3-yaml'),
     Copy('shlax/', 'setup.py', '/app'),
     Pip('/app'),
     commit='yourlabs/shlax',