diff --git a/server/fishtest/api.py b/server/fishtest/api.py
index 451f354d1..ecf34fe80 100644
--- a/server/fishtest/api.py
+++ b/server/fishtest/api.py
@@ -30,7 +30,7 @@
 depending on how frequently the main instance flushes its run cache.
 """
 
-WORKER_VERSION = 229
+WORKER_VERSION = 230
 
 """
 begin api_schema
diff --git a/server/fishtest/rundb.py b/server/fishtest/rundb.py
index 6b26e2989..dad9a9ee6 100644
--- a/server/fishtest/rundb.py
+++ b/server/fishtest/rundb.py
@@ -747,7 +747,7 @@ def aggregate_unfinished_runs(self, username=None):
                     nps += concurrency * task["worker_info"]["nps"]
                     if task["worker_info"]["nps"] != 0:
                         games_per_minute += (
-                            (task["worker_info"]["nps"] / 640000)
+                            (task["worker_info"]["nps"] / 691680)
                             * (60.0 / estimate_game_duration(run["args"]["tc"]))
                             * (
                                 int(task["worker_info"]["concurrency"])
diff --git a/server/utils/delta_update_users.py b/server/utils/delta_update_users.py
index 15bcc0e6a..58ff8ebca 100644
--- a/server/utils/delta_update_users.py
+++ b/server/utils/delta_update_users.py
@@ -45,10 +45,10 @@ def initialize_info(rundb, clear_stats):
 
 
 def compute_games_rates(rundb, info_tuple):
-    # 1184000 nps is the reference core, also set in rundb.py and games.py
+    # use the reference core nps, also set in rundb.py and games.py
     for machine in rundb.get_machines():
         games_per_hour = (
-            (machine["nps"] / 640000)
+            (machine["nps"] / 691680)
             * (3600.0 / estimate_game_duration(machine["run"]["args"]["tc"]))
             * (int(machine["concurrency"]) // machine["run"]["args"].get("threads", 1))
         )
diff --git a/worker/games.py b/worker/games.py
index 84bd212ef..9b031b66d 100644
--- a/worker/games.py
+++ b/worker/games.py
@@ -1371,15 +1371,16 @@ def parse_options(s):
         games_concurrency * threads,
     )
 
-    if base_nps < 231000 / (1 + math.tanh((worker_concurrency - 1) / 8)):
+    if base_nps < 208082 / (1 + math.tanh((worker_concurrency - 1) / 8)):
         raise WorkerException(
             "This machine is too slow ({} nps / thread) to run fishtest effectively - sorry!".format(
                 base_nps
             )
         )
-    # 1184000 nps is the reference core benched with respect to SF 11,
+    # fishtest with Stockfish 11 had 1.6 Mnps as reference nps and
+    # 0.7 Mnps as threshold for the slow worker.
     # also set in rundb.py and delta_update_users.py
-    factor = 640000 / base_nps
+    factor = 691680 / base_nps
 
     # Adjust CPU scaling.
     _, tc_limit_ltc = adjust_tc("60+0.6", factor)
diff --git a/worker/sri.txt b/worker/sri.txt
index 2fea705bb..df7666c51 100644
--- a/worker/sri.txt
+++ b/worker/sri.txt
@@ -1 +1 @@
-{"__version": 229, "updater.py": "Mg+pWOgGA0gSo2TuXuuLCWLzwGwH91rsW1W3ixg3jYauHQpRMtNdGnCfuD1GqOhV", "worker.py": "ZqWya/LcB5xq0sj+M/D1CApoBt0vGSTtBeaBLs3sFDEXezhfM0xdJCMeXlJZWN+5", "games.py": "C0yeQ5Oh8eyca64NntP+oetpWAjCvPSWdMyNCGSeS4o9yJN41L4SkL9rTx3z716m"}
+{"__version": 230, "updater.py": "Mg+pWOgGA0gSo2TuXuuLCWLzwGwH91rsW1W3ixg3jYauHQpRMtNdGnCfuD1GqOhV", "worker.py": "2Z0LG7EAR0cmOY7yHDDsynebLO8yXmhwaBqjTAJpDDZlumO5o2xYMxglfCRg1/Bg", "games.py": "TzWMwq9hBmAHB0C7JAOvsI+pBvttQiPC4ul5FsOzozJ9lmZl/NutFbvWk8sobJr8"}
diff --git a/worker/worker.py b/worker/worker.py
index 51cd9f13b..00fe7a39b 100644
--- a/worker/worker.py
+++ b/worker/worker.py
@@ -55,7 +55,7 @@
 # Several packages are called "expression".
 # So we make sure to use the locally installed one.
 
-WORKER_VERSION = 229
+WORKER_VERSION = 230
 FILE_LIST = ["updater.py", "worker.py", "games.py"]
 HTTP_TIMEOUT = 30.0
 INITIAL_RETRY_TIME = 15.0