diff --git a/src/core.py b/src/core.py
index 0d53f5b6..3b0b490e 100644
--- a/src/core.py
+++ b/src/core.py
@@ -1637,7 +1637,7 @@ class Core(object):
             version = '%s is running %s version %s on %s' % (jid,
                                                              res.get('name') or _('an unknown software'),
                                                              res.get('version') or _('unknown'),
-                                                             res.get('os') or _('on an unknown platform'))
+                                                             res.get('os') or _('an unknown platform'))
             self.information(version, 'Info')
 
         args = common.shell_split(arg)
diff --git a/src/tabs.py b/src/tabs.py
index b47d8e29..0c9c2047 100644
--- a/src/tabs.py
+++ b/src/tabs.py
@@ -991,7 +991,7 @@ class MucTab(ChatTab):
             version = '%s is running %s version %s on %s' % (jid,
                          res.get('name') or _('an unknown software'),
                          res.get('version') or _('unknown'),
-                         res.get('os') or _('on an unknown platform'))
+                         res.get('os') or _('an unknown platform'))
             self.core.information(version, 'Info')
 
         if not arg:
@@ -1922,7 +1922,7 @@ class PrivateTab(ChatTab):
             version = '%s is running %s version %s on %s' % (jid,
                                                              res.get('name') or _('an unknown software'),
                                                              res.get('version') or _('unknown'),
-                                                             res.get('os') or _('on an unknown platform'))
+                                                             res.get('os') or _('an unknown platform'))
             self.core.information(version, 'Info')
         if arg:
             return self.core.command_version(arg)
@@ -3127,7 +3127,7 @@ class ConversationTab(ChatTab):
             version = '%s is running %s version %s on %s' % (jid,
                                                              res.get('name') or _('an unknown software'),
                                                              res.get('version') or _('unknown'),
-                                                             res.get('os') or _('on an unknown platform'))
+                                                             res.get('os') or _('an unknown platform'))
             self.core.information(version, 'Info')
         if arg:
             return self.core.command_version(arg)