diff --git a/scheme/time.sld b/scheme/time.sld
index c7d11c43..bf28fc1e 100644
--- a/scheme/time.sld
+++ b/scheme/time.sld
@@ -3,6 +3,7 @@
     current-second
     current-jiffy
     jiffies-per-second
+    sin ;; just temporary, will be relocated
   )
   (import (scheme base) 
   )
@@ -24,4 +25,14 @@
       "(void *data, int argc, closure _, object k)"
       " make_int(box, CLOCKS_PER_SEC);
         return_closcall1(data, k, &box); ")
+    (define-c sin
+      "(void *data, int argc, closure _, object k, object z)"
+      " make_double(d, 0.0);
+        Cyc_check_num(data, z);
+        if (type_of(z) == integer_tag) {
+          d.value = sin(((integer_type *)z)->value);
+        } else {
+          d.value = sin(((double_type *)z)->value);
+        }
+        return_closcall1(data, k, &d); ")
   ))