Fixed bug #1081: file.seek allows float arguments
diff --git a/Lib/io.py b/Lib/io.py
index c2f5d3e..d9550ae 100644
--- a/Lib/io.py
+++ b/Lib/io.py
@@ -694,6 +694,8 @@
         return n
 
     def seek(self, pos, whence=0):
+        if not isinstance(pos, int):
+            raise TypeError("an integer is required")
         if whence == 0:
             self._pos = max(0, pos)
         elif whence == 1: