diff --git a/asdf.lisp b/asdf.lisp
index 7d5b6a0a2920ad1e14710be602ee42bf442745ae..cc1c3c4997df3f16885390a3192478ef2a29a981 100644
--- a/asdf.lisp
+++ b/asdf.lisp
@@ -251,7 +251,7 @@
   ;; This parameter isn't actually user-visible
   ;; -- please use the exported function ASDF:ASDF-VERSION below.
   ;; the 1+ hair is to ensure that we don't do an inadvertent find and replace
-  (subseq "VERSION:1.643" (1+ (length "VERSION"))))
+  (subseq "VERSION:1.644" (1+ (length "VERSION"))))
 
 (defun asdf-version ()
   "Exported interface to the version of ASDF currently installed. A string.