diff --git a/src/code/rand-xoroshiro.lisp b/src/code/rand-xoroshiro.lisp
index a7af285ea2d7c22eebdd095e7383b7d63d983130..68b567d9407faaa9c160895b3e717a796bec0389 100644
--- a/src/code/rand-xoroshiro.lisp
+++ b/src/code/rand-xoroshiro.lisp
@@ -85,7 +85,7 @@
 		 (aref state 1) (make-double s1))
 	   state))))
 
-(defun vec-init-xoro-state (key &optional state)
+(defun vec-init-xoro-state (key &optional (state (make-array 2 :element-type 'double-float)))
   (declare (type (array (unsigned-byte 64) (2)) key)
 	   (type (simple-array double-float (2)) state))
   (flet ((make-double (x)