1 files changed, 9 insertions, 0 deletions

diff --git a/src/Network/BitTorrent/Core/PeerId.hs b/src/Network/BitTorrent/Core/PeerId.hs
index 1ae55913..8883656b 100644
--- a/src/Network/BitTorrent/Core/PeerId.hs
+++ b/src/Network/BitTorrent/Core/PeerId.hs
@@ -49,6 +49,7 @@ import Data.List as L
 import Data.Maybe       (fromMaybe)
 import Data.Monoid
 import Data.Serialize as S
+import Data.String
 import Data.Time.Clock  (getCurrentTime)
 import Data.Time.Format (formatTime)
 import Data.URLEncoded
@@ -74,6 +75,14 @@ instance Serialize PeerId where
 instance URLShow PeerId where
   urlShow = BC.unpack . getPeerId
 
+instance IsString PeerId where
+  fromString str
+      | BS.length bs == 20 = PeerId bs
+      |      otherwise     = error $ "Peer id should be 20 bytes long: "
+                                  ++ show str
+    where
+      bs = fromString str
+
 -- | Format peer id in human readable form.
 ppPeerId :: PeerId -> Doc
 ppPeerId = text . BC.unpack . getPeerId