diff --git a/scheme/base.sld b/scheme/base.sld
index 9c732e48..4b101d77 100644
--- a/scheme/base.sld
+++ b/scheme/base.sld
@@ -35,6 +35,7 @@
     floor-remainder
     even?
     exact-integer?
+    ;exact-integer-sqrt
     exact?
     inexact?
     odd?
@@ -1043,6 +1044,15 @@
         (if (>= res 0) res (+ res b)))))
   (define (odd? num)   (= (modulo num 2) 1))
   (define (even? num)  (= (modulo num 2) 0))
+;  ;; from mosh
+;  (define (exact-integer-sqrt k)
+;    (unless (and (exact? k)
+;                 (integer? k)
+;                 (not (negative? k)))
+;      (error "exact non-negative integer required" k))
+;    (let* ((s (exact (truncate (sqrt k))))
+;           (r (- k (* s s))))
+;      (values s r)))
   (define (exact-integer? num)
     (and (exact? num) (integer? num)))
   (define-c exact?