diff --git a/compiler/fndb.lisp b/compiler/fndb.lisp
index 4dfa5bda2080ac6bf5132dd1d729c47180db7d5b..4eca576073969d0c8aa6a9b9517acadabf7bb90a 100644
--- a/compiler/fndb.lisp
+++ b/compiler/fndb.lisp
@@ -239,7 +239,7 @@
 (defknown copy-symbol (symbol &optional t) symbol (flushable))
 (defknown gensym (&optional (or string unsigned-byte)) symbol ())
 (defknown gentemp (&optional string package) symbol)
-(defknown symbol-package (symbol) package (flushable))
+(defknown symbol-package (symbol) (or package null) (flushable))
 (defknown keywordp (t) boolean (flushable))	  ; If someone uninterns it...