diff --git a/basis/io/backend/unix/unix.factor b/basis/io/backend/unix/unix.factor
index 3245d80d4e..ebb8f1ec05 100644
--- a/basis/io/backend/unix/unix.factor
+++ b/basis/io/backend/unix/unix.factor
@@ -50,7 +50,7 @@ M: fd cancel-operation ( fd -- )
     ] if ;
 
 M: unix tell-handle ( handle -- n )
-    fd>> SEEK_SET 0 lseek [ io-error ] [ ] bi ;
+    fd>> 0 SEEK_CUR lseek [ io-error ] [ ] bi ;
 
 M: unix seek-handle ( n seek-type handle -- )
     swap {
diff --git a/basis/io/ports/ports.factor b/basis/io/ports/ports.factor
index 7ecb420478..8cdd1d97bd 100644
--- a/basis/io/ports/ports.factor
+++ b/basis/io/ports/ports.factor
@@ -130,7 +130,7 @@ HOOK: seek-handle os ( n seek-type handle -- )
 M: buffered-port stream-tell ( stream -- n )
     [ check-disposed ]
     [ handle>> tell-handle ]
-    [ buffer>> pos>> ] tri + ;
+    [ [ buffer>> size>> - 0 max ] [ buffer>> pos>> ] bi + ] tri ;
 
 M: input-port stream-seek ( n seek-type stream -- )
     [ check-disposed ]