diff --git a/README.md b/README.md
index 0a87aab..cb64e9f 100644
--- a/README.md
+++ b/README.md
@@ -23,7 +23,7 @@ Other depencies include:
 * euca2ools
 * xfsprogs (If you want to use XFS as a filesystem)
 Also the following python libraries are required:
-* **boto**
+* **boto** ([version 2.14.0 or higher](https://github.com/boto/boto))
 * **jsonschema** ([version 2.0.0](https://pypi.python.org/pypi/jsonschema), only available through pip)
 * **termcolor**
 * **fysom**
diff --git a/base/manifest-schema.json b/base/manifest-schema.json
index ad37a67..d74b36a 100644
--- a/base/manifest-schema.json
+++ b/base/manifest-schema.json
@@ -45,7 +45,7 @@
 				"sources": {
 					"type": "object",
 					"patternProperties": {
-						"^\\w+$": {
+						"^[^\/\\0]+$": {
 							"type": "array",
 							"items": {
 								"type": "string",
diff --git a/providers/kvm/tasks/virtio.py b/providers/kvm/tasks/virtio.py
index 5c718cc..a3d2370 100644
--- a/providers/kvm/tasks/virtio.py
+++ b/providers/kvm/tasks/virtio.py
@@ -1,7 +1,5 @@
 from base import Task
 from common import phases
-from common.tasks.packages import InstallPackages
-from common.exceptions import TaskError
 import os
 
 
@@ -11,9 +9,8 @@ class VirtIO(Task):
 
 	@classmethod
 	def run(cls, info):
-		from common.tools import log_call
-		modules = os.path.join(info.root,'/etc/initramfs-tools/modules')
+		modules = os.path.join(info.root, '/etc/initramfs-tools/modules')
 		with open(modules, "a") as modules_file:
-			modules_file.write("\n");
+			modules_file.write("\n")
 			for module in info.manifest.bootstrapper.get('virtio', []):
 				modules_file.write(module+"\n")