diff --git a/src/or/circuitlist.c b/src/or/circuitlist.c
index 50caf370d9..bb74594ecd 100644
--- a/src/or/circuitlist.c
+++ b/src/or/circuitlist.c
@@ -678,7 +678,7 @@ origin_circuit_new(void)
 
   init_circuit_base(TO_CIRCUIT(circ));
 
-  get_circuit_build_times_mutable()->last_circ_at = approx_time();
+  circuit_build_times_update_last_circ(get_circuit_build_times_mutable());
 
   return circ;
 }
diff --git a/src/or/circuitstats.c b/src/or/circuitstats.c
index e7b4b36bbd..8fdef58858 100644
--- a/src/or/circuitstats.c
+++ b/src/or/circuitstats.c
@@ -18,6 +18,10 @@
 #undef log
 #include <math.h>
 
+static void cbt_control_event_buildtimeout_set(
+                                  const circuit_build_times_t *cbt,
+                                  buildtimeout_set_event_t type);
+
 #define CBT_BIN_TO_MS(bin) ((bin)*CBT_BIN_WIDTH + (CBT_BIN_WIDTH/2))
 
 /** Global list of circuit build times */
@@ -505,7 +509,7 @@ circuit_build_times_init(circuit_build_times_t *cbt)
     cbt->liveness.timeouts_after_firsthop = NULL;
   }
   cbt->close_ms = cbt->timeout_ms = circuit_build_times_get_initial_timeout();
-  control_event_buildtimeout_set(cbt, BUILDTIMEOUT_SET_EVENT_RESET);
+  cbt_control_event_buildtimeout_set(cbt, BUILDTIMEOUT_SET_EVENT_RESET);
 }
 
 /**
@@ -1369,7 +1373,7 @@ circuit_build_times_network_check_changed(circuit_build_times_t *cbt)
                   = circuit_build_times_get_initial_timeout();
   }
 
-  control_event_buildtimeout_set(cbt, BUILDTIMEOUT_SET_EVENT_RESET);
+  cbt_control_event_buildtimeout_set(cbt, BUILDTIMEOUT_SET_EVENT_RESET);
 
   log_notice(LD_CIRC,
             "Your network connection speed appears to have changed. Resetting "
@@ -1551,7 +1555,7 @@ circuit_build_times_set_timeout(circuit_build_times_t *cbt)
     }
   }
 
-  control_event_buildtimeout_set(cbt, BUILDTIMEOUT_SET_EVENT_COMPUTED);
+  cbt_control_event_buildtimeout_set(cbt, BUILDTIMEOUT_SET_EVENT_COMPUTED);
 
   timeout_rate = circuit_build_times_timeout_rate(cbt);
 
@@ -1597,3 +1601,44 @@ circuitbuild_running_unit_tests(void)
 }
 #endif
 
+void
+circuit_build_times_update_last_circ(circuit_build_times_t *cbt)
+{
+  cbt->last_circ_at = approx_time();
+}
+
+static void
+cbt_control_event_buildtimeout_set(const circuit_build_times_t *cbt,
+                                   buildtimeout_set_event_t type)
+{
+  char *args = NULL;
+  double qnt;
+
+  switch(type) {
+    case BUILDTIMEOUT_SET_EVENT_RESET:
+    case BUILDTIMEOUT_SET_EVENT_SUSPENDED:
+    case BUILDTIMEOUT_SET_EVENT_DISCARD:
+      qnt = 1.0;
+      break;
+    case BUILDTIMEOUT_SET_EVENT_COMPUTED:
+    case BUILDTIMEOUT_SET_EVENT_RESUME:
+    default:
+      qnt = circuit_build_times_quantile_cutoff();
+      break;
+  }
+
+  tor_asprintf(&args, "TOTAL_TIMES=%lu "
+               "TIMEOUT_MS=%lu XM=%lu ALPHA=%f CUTOFF_QUANTILE=%f "
+               "TIMEOUT_RATE=%f CLOSE_MS=%lu CLOSE_RATE=%f",
+               (unsigned long)cbt->total_build_times,
+               (unsigned long)cbt->timeout_ms,
+               (unsigned long)cbt->Xm, cbt->alpha, qnt,
+               circuit_build_times_timeout_rate(cbt),
+               (unsigned long)cbt->close_ms,
+               circuit_build_times_close_rate(cbt));
+
+  control_event_buildtimeout_set(type, args);
+
+  tor_free(args);
+
+}
diff --git a/src/or/circuitstats.h b/src/or/circuitstats.h
index 196af3fab4..38a7e4efa8 100644
--- a/src/or/circuitstats.h
+++ b/src/or/circuitstats.h
@@ -40,6 +40,8 @@ void circuit_build_times_new_consensus_params(circuit_build_times_t *cbt,
 double circuit_build_times_timeout_rate(const circuit_build_times_t *cbt);
 double circuit_build_times_close_rate(const circuit_build_times_t *cbt);
 
+void circuit_build_times_update_last_circ(circuit_build_times_t *cbt);
+
 #ifdef CIRCUITSTATS_PRIVATE
 STATIC double circuit_build_times_calculate_timeout(circuit_build_times_t *cbt,
                                              double quantile);
@@ -65,5 +67,32 @@ void circuit_build_times_network_is_live(circuit_build_times_t *cbt);
 int circuit_build_times_network_check_live(const circuit_build_times_t *cbt);
 void circuit_build_times_network_circ_success(circuit_build_times_t *cbt);
 
+#ifdef CIRCUITSTATS_PRIVATE
+/** Structure for circuit build times history */
+struct circuit_build_times_s{
+  /** The circular array of recorded build times in milliseconds */
+  build_time_t circuit_build_times[CBT_NCIRCUITS_TO_OBSERVE];
+  /** Current index in the circuit_build_times circular array */
+  int build_times_idx;
+  /** Total number of build times accumulated. Max CBT_NCIRCUITS_TO_OBSERVE */
+  int total_build_times;
+  /** Information about the state of our local network connection */
+  network_liveness_t liveness;
+  /** Last time we built a circuit. Used to decide to build new test circs */
+  time_t last_circ_at;
+  /** "Minimum" value of our pareto distribution (actually mode) */
+  build_time_t Xm;
+  /** alpha exponent for pareto dist. */
+  double alpha;
+  /** Have we computed a timeout? */
+  int have_computed_timeout;
+  /** The exact value for that timeout in milliseconds. Stored as a double
+   * to maintain precision from calculations to and from quantile value. */
+  double timeout_ms;
+  /** How long we wait before actually closing the circuit. */
+  double close_ms;
+};
+#endif
+
 #endif
 
diff --git a/src/or/control.c b/src/or/control.c
index 81df00cf92..fc4809b399 100644
--- a/src/or/control.c
+++ b/src/or/control.c
@@ -4163,32 +4163,26 @@ control_event_newconsensus(const networkstatus_t *consensus)
 
 /** Called when we compute a new circuitbuildtimeout */
 int
-control_event_buildtimeout_set(const circuit_build_times_t *cbt,
-                        buildtimeout_set_event_t type)
+control_event_buildtimeout_set(buildtimeout_set_event_t type,
+                               const char *args)
 {
   const char *type_string = NULL;
-  double qnt;
 
   if (!control_event_is_interesting(EVENT_BUILDTIMEOUT_SET))
     return 0;
 
-  qnt = circuit_build_times_quantile_cutoff();
-
   switch (type) {
     case BUILDTIMEOUT_SET_EVENT_COMPUTED:
       type_string = "COMPUTED";
       break;
     case BUILDTIMEOUT_SET_EVENT_RESET:
       type_string = "RESET";
-      qnt = 1.0;
       break;
     case BUILDTIMEOUT_SET_EVENT_SUSPENDED:
       type_string = "SUSPENDED";
-      qnt = 1.0;
       break;
     case BUILDTIMEOUT_SET_EVENT_DISCARD:
       type_string = "DISCARD";
-      qnt = 1.0;
       break;
     case BUILDTIMEOUT_SET_EVENT_RESUME:
       type_string = "RESUME";
@@ -4199,15 +4193,8 @@ control_event_buildtimeout_set(const circuit_build_times_t *cbt,
   }
 
   send_control_event(EVENT_BUILDTIMEOUT_SET, ALL_FORMATS,
-                     "650 BUILDTIMEOUT_SET %s TOTAL_TIMES=%lu "
-                     "TIMEOUT_MS=%lu XM=%lu ALPHA=%f CUTOFF_QUANTILE=%f "
-                     "TIMEOUT_RATE=%f CLOSE_MS=%lu CLOSE_RATE=%f\r\n",
-                     type_string, (unsigned long)cbt->total_build_times,
-                     (unsigned long)cbt->timeout_ms,
-                     (unsigned long)cbt->Xm, cbt->alpha, qnt,
-                     circuit_build_times_timeout_rate(cbt),
-                     (unsigned long)cbt->close_ms,
-                     circuit_build_times_close_rate(cbt));
+                     "650 BUILDTIMEOUT_SET %s %s\r\n",
+                     type_string, args);
 
   return 0;
 }
diff --git a/src/or/control.h b/src/or/control.h
index be9476ea3f..1a44768cee 100644
--- a/src/or/control.h
+++ b/src/or/control.h
@@ -73,8 +73,8 @@ int control_event_server_status(int severity, const char *format, ...)
 int control_event_guard(const char *nickname, const char *digest,
                         const char *status);
 int control_event_conf_changed(const smartlist_t *elements);
-int control_event_buildtimeout_set(const circuit_build_times_t *cbt,
-                                   buildtimeout_set_event_t type);
+int control_event_buildtimeout_set(buildtimeout_set_event_t type,
+                                   const char *args);
 int control_event_signal(uintptr_t signal);
 
 int init_control_cookie_authentication(int enabled);
diff --git a/src/or/or.h b/src/or/or.h
index 2daf12b82d..041421ed42 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -4471,30 +4471,7 @@ typedef struct {
   int after_firsthop_idx;
 } network_liveness_t;
 
-/** Structure for circuit build times history */
-typedef struct {
-  /** The circular array of recorded build times in milliseconds */
-  build_time_t circuit_build_times[CBT_NCIRCUITS_TO_OBSERVE];
-  /** Current index in the circuit_build_times circular array */
-  int build_times_idx;
-  /** Total number of build times accumulated. Max CBT_NCIRCUITS_TO_OBSERVE */
-  int total_build_times;
-  /** Information about the state of our local network connection */
-  network_liveness_t liveness;
-  /** Last time we built a circuit. Used to decide to build new test circs */
-  time_t last_circ_at;
-  /** "Minimum" value of our pareto distribution (actually mode) */
-  build_time_t Xm;
-  /** alpha exponent for pareto dist. */
-  double alpha;
-  /** Have we computed a timeout? */
-  int have_computed_timeout;
-  /** The exact value for that timeout in milliseconds. Stored as a double
-   * to maintain precision from calculations to and from quantile value. */
-  double timeout_ms;
-  /** How long we wait before actually closing the circuit. */
-  double close_ms;
-} circuit_build_times_t;
+typedef struct circuit_build_times_s circuit_build_times_t;
 
 /********************************* config.c ***************************/