diff --git a/Modules/_fileio.c b/Modules/_fileio.c
index 5b840c0..7a71837 100644
--- a/Modules/_fileio.c
+++ b/Modules/_fileio.c
@@ -55,6 +55,9 @@
 
 #define PyFileIO_Check(op) (PyObject_TypeCheck((op), &PyFileIO_Type))
 
+static PyObject *
+portable_lseek(int fd, PyObject *posobj, int whence);
+
 /* Returns 0 on success, -1 with exception set on failure. */
 static int
 internal_close(PyFileIOObject *self)
@@ -315,6 +318,16 @@
 			goto error;
 	}
 
+	if (append) {
+		/* For consistent behaviour, we explicitly seek to the
+		   end of file (otherwise, it might be done only on the
+		   first write()). */
+		PyObject *pos = portable_lseek(self->fd, NULL, 2);
+		if (pos == NULL)
+			goto error;
+		Py_DECREF(pos);
+	}
+
 	goto done;
 
  error: