diff --git a/src/grovel/invoke.lisp b/src/grovel/invoke.lisp
index 116dafec3852b941429444904d17f8a7339068aa..e5e5d63ffd8ff71eca205d172fe18aba930af4c0 100644
--- a/src/grovel/invoke.lisp
+++ b/src/grovel/invoke.lisp
@@ -39,7 +39,7 @@
 #+abcl
 (defun %invoke (command arglist)
   (let ((cmdline (reduce (lambda (str1 str2)
-                           (concatenate 'string str1 #\Space str2))
+                           (concatenate 'string str1 " " str2))
                          arglist :initial-value command))
         (stream (make-string-output-stream)))
     (values (ext:run-shell-command cmdline :output stream)