diff --git a/pkg/urbit/jets/a/mod.c b/pkg/urbit/jets/a/mod.c
index f80834e1b8..80c8923ca6 100644
--- a/pkg/urbit/jets/a/mod.c
+++ b/pkg/urbit/jets/a/mod.c
@@ -10,15 +10,10 @@
   u3qa_mod(u3_atom a,
            u3_atom b)
   {
-#if 0
-    if ( b == 3 && a == 2684227708 ) {
-      printf("dword at 0x27ff84ff8 is %" PRIu64 "\r\n", *(c3_d *)0x27ff84ff8);
-      *(c3_d *)0x27ff84ff8 = 25;
-      printf("see, we modified it\r\n");
-    }
-#endif
     if ( 0 == b ) {
       return u3m_bail(c3__exit);
+    } else if ( _(u3a_is_cat(a)) && _(u3a_is_cat(b)) ) {
+      return a % b;
     } else {
       mpz_t a_mp, b_mp;