diff --git a/libtransmission/peer-mgr.c b/libtransmission/peer-mgr.c
index dc04d1799..a1beb6ff1 100644
--- a/libtransmission/peer-mgr.c
+++ b/libtransmission/peer-mgr.c
@@ -2494,11 +2494,21 @@ tr_peerUpdateProgress( tr_torrent * tor, tr_peer * peer )
         const float true_count = tr_bitfieldCountTrueBits( have );
 
         if( tr_torrentHasMetadata( tor ) )
+        {
             peer->progress = true_count / tor->info.pieceCount;
+        }
         else /* without pieceCount, this result is only a best guess... */
+        {
             peer->progress = true_count / ( have->bit_count + 1 );
+        }
     }
 
+    /* clamp the progress range */
+    if ( peer->progress < 0.0 )
+        peer->progress = 0.0;
+    if ( peer->progress > 1.0 )
+        peer->progress = 1.0;
+
     if( peer->atom && ( peer->progress >= 1.0 ) )
         atomSetSeed( tor->torrentPeers, peer->atom );
 }