diff --git a/src/sugar3/bundle/activitybundle.py b/src/sugar3/bundle/activitybundle.py
index c065fa4b..0d4a9d11 100644
--- a/src/sugar3/bundle/activitybundle.py
+++ b/src/sugar3/bundle/activitybundle.py
@@ -139,6 +139,9 @@ class ActivityBundle(Bundle):
                     'Activity bundle %s does not specify a bundle id' %
                     self._path)
 
+        if ' ' in self._bundle_id:
+            raise MalformedBundleException('Space in bundle_id')
+
         if cp.has_option(section, 'name'):
             self._name = cp.get(section, 'name')
         else: