diff --git a/pkg/urbit/worker/main.c b/pkg/urbit/worker/main.c
index 536e46342a..fe8bdaf4ce 100644
--- a/pkg/urbit/worker/main.c
+++ b/pkg/urbit/worker/main.c
@@ -24,10 +24,10 @@
 
 #include "ur/hashcons.h"
 
-static u3_serf       u3V;             //  one serf per process
-static u3_moat     inn_u;             //  input stream
-static u3_mojo     out_u;             //  output stream
-static ur_dict32_t dic_u;             //  cue dictionary
+static u3_serf        u3V;             //  one serf per process
+static u3_moat      inn_u;             //  input stream
+static u3_mojo      out_u;             //  output stream
+static u3_cue_sill* sil_u;             //  cue handle
 
 #undef SERF_TRACE_JAM
 #undef SERF_TRACE_CUE
@@ -107,8 +107,8 @@ _cw_serf_step_trace(void)
 static void
 _cw_serf_writ(void* vod_p, c3_d len_d, c3_y* byt_y)
 {
-  u3_noun ret, jar;
-  c3_o  ret_o;
+  u3_weak jar;
+  u3_noun ret;
 
   _cw_serf_step_trace();
 
@@ -116,16 +116,13 @@ _cw_serf_writ(void* vod_p, c3_d len_d, c3_y* byt_y)
   u3t_event_trace("serf ipc cue", 'B');
 #endif
 
-  ret_o = u3s_cue_xeno_unsafe(&dic_u, len_d, byt_y, &jar);
-  //  XX check if the dictionary grew too much and shrink?
-  //
-  ur_dict32_wipe(&dic_u);
+  jar = u3s_cue_sill_with(sil_u, len_d, byt_y);
 
 #ifdef SERF_TRACE_CUE
   u3t_event_trace("serf ipc cue", 'E');
 #endif
 
-  if (  (c3n == ret_o)
+  if (  (u3_none == jar)
      || (c3n == u3_serf_writ(&u3V, jar, &ret)) )
   {
     _cw_serf_fail(0, -1, "bad jar");
@@ -165,7 +162,7 @@ _cw_serf_stdio(c3_i* inn_i, c3_i* out_i)
 static void
 _cw_serf_exit(void)
 {
-  ur_dict_free((ur_dict_t*)&dic_u);
+  u3s_cue_sill_done(sil_u);
   u3t_trace_close();
 }
 
@@ -239,7 +236,7 @@ _cw_serf_commence(c3_i argc, c3_c* argv[])
     uv_stream_set_blocking((uv_stream_t*)&out_u.pyp_u, 1);
   }
 
-  ur_dict32_grow((ur_root_t*)0, &dic_u, ur_fib10, ur_fib11);
+  sil_u = u3s_cue_sill_init();
 
   //  set up writing
   //