--- a/contrib/asdf/asdf.lisp
+++ b/contrib/asdf/asdf.lisp
@@ -1601,7 +1601,7 @@
      '(:cygwin (:win :windows :mswindows :win32 :mingw32) ;; try cygwin first!
        (:linux :linux :linux-target) ;; for GCL at least, must appear before :bsd
        (:macosx :macosx :darwin :darwin-target :apple) ; also before :bsd
-       (:solaris :solaris :sunos) (:bsd :bsd :freebsd :netbsd :openbsd) :unix
+       (:solaris :solaris :sunos) (:bsd :bsd :freebsd :netbsd :openbsd :dragonfly) :unix
        :genera)))
 
   (defun architecture ()