diff --git a/src/main/entity.cl b/src/main/entity.cl
index 3b6045f..993bf49 100644
--- a/src/main/entity.cl
+++ b/src/main/entity.cl
@@ -72,9 +72,11 @@
   (setf (slot-value e 'content-length) (stream-entity-length e)))
 
 (defmethod render-entity-body ((entity stream-entity-mixin) stream)
+  (declare (type stream stream))
   (with-open-stream (in-stream (stream-entity-stream entity))
+    (declare (type stream in-stream))
     (with-io-buffer (buffer)
-      (loop for length = (read-sequence buffer in-stream)
+      (loop for length of-type fixnum = (read-sequence buffer in-stream)
 	    until (zerop length)
 	    do
 	    (write-sequence buffer stream :end length)))))