diff --git a/packages/core/clockworker.js b/packages/core/clockworker.js
index 7ca04528..db9ef123 100644
--- a/packages/core/clockworker.js
+++ b/packages/core/clockworker.js
@@ -1,5 +1,5 @@
 // eslint-disable-next-line no-undef
-importScripts('./zyklus.js');
+importScripts('./neozyklus.js');
 
 function getTime() {
   const precision = 10 ** 4;
diff --git a/packages/core/cyclist.mjs b/packages/core/cyclist.mjs
index f024c464..a8ccd30f 100644
--- a/packages/core/cyclist.mjs
+++ b/packages/core/cyclist.mjs
@@ -4,7 +4,7 @@ Copyright (C) 2022 Strudel contributors - see <https://github.com/tidalcycles/st
 This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
 
-import * as createClock from './zyklus.js';
+import createClock from './zyklus';
 import { logger } from './logger.mjs';
 
 export class Cyclist {
diff --git a/packages/core/neozyklus.js b/packages/core/neozyklus.js
new file mode 100644
index 00000000..9ec4e775
--- /dev/null
+++ b/packages/core/neozyklus.js
@@ -0,0 +1,46 @@
+// used to consistently schedule events, for use in a service worker - see <https://github.com/tidalcycles/strudel/blob/main/packages/core/clockworker.mjs>
+this.createClock = (
+  getTime,
+  callback, // called slightly before each cycle
+  duration = 0.05, // duration of each cycle
+  interval = 0.1, // interval between callbacks
+  overlap = 0.1, // overlap between callbacks
+) => {
+  let tick = 0; // counts callbacks
+  let phase = 0; // next callback time
+  let precision = 10 ** 4; // used to round phase
+  let minLatency = 0.01;
+  const setDuration = (setter) => (duration = setter(duration));
+  overlap = overlap || interval / 2;
+  const onTick = () => {
+    const t = getTime();
+    const lookahead = t + interval + overlap; // the time window for this tick
+    if (phase === 0) {
+      phase = t + minLatency;
+    }
+    // callback as long as we're inside the lookahead
+    while (phase < lookahead) {
+      phase = Math.round(phase * precision) / precision;
+      phase >= t && callback(phase, duration, tick, t);
+      phase < t && console.log('TOO LATE', phase); // what if latency is added from outside?
+      phase += duration; // increment phase by duration
+      tick++;
+    }
+  };
+  let intervalID;
+  const start = () => {
+    clear(); // just in case start was called more than once
+    onTick();
+    intervalID = setInterval(onTick, interval * 1000);
+  };
+  const clear = () => intervalID !== undefined && clearInterval(intervalID);
+  const pause = () => clear();
+  const stop = () => {
+    tick = 0;
+    phase = 0;
+    clear();
+  };
+  const getPhase = () => phase;
+  // setCallback
+  return { setDuration, start, stop, pause, duration, interval, getPhase, minLatency };
+};
diff --git a/packages/core/zyklus.js b/packages/core/zyklus.js
index 7a9c7fa5..3d25b054 100644
--- a/packages/core/zyklus.js
+++ b/packages/core/zyklus.js
@@ -1,50 +1,49 @@
 // will move to https://github.com/felixroos/zyklus
 // TODO: started flag
-//TODO: fix tests not understanding "self"
-if (typeof self !== 'undefined') {
-  self.createClock = (
-    getTime,
-    callback, // called slightly before each cycle
-    duration = 0.05, // duration of each cycle
-    interval = 0.1, // interval between callbacks
-    overlap = 0.1, // overlap between callbacks
-  ) => {
-    let tick = 0; // counts callbacks
-    let phase = 0; // next callback time
-    let precision = 10 ** 4; // used to round phase
-    let minLatency = 0.01;
-    const setDuration = (setter) => (duration = setter(duration));
-    overlap = overlap || interval / 2;
-    const onTick = () => {
-      const t = getTime();
-      const lookahead = t + interval + overlap; // the time window for this tick
-      if (phase === 0) {
-        phase = t + minLatency;
-      }
-      // callback as long as we're inside the lookahead
-      while (phase < lookahead) {
-        phase = Math.round(phase * precision) / precision;
-        phase >= t && callback(phase, duration, tick, t);
-        phase < t && console.log('TOO LATE', phase); // what if latency is added from outside?
-        phase += duration; // increment phase by duration
-        tick++;
-      }
-    };
-    let intervalID;
-    const start = () => {
-      clear(); // just in case start was called more than once
-      onTick();
-      intervalID = setInterval(onTick, interval * 1000);
-    };
-    const clear = () => intervalID !== undefined && clearInterval(intervalID);
-    const pause = () => clear();
-    const stop = () => {
-      tick = 0;
-      phase = 0;
-      clear();
-    };
-    const getPhase = () => phase;
-    // setCallback
-    return { setDuration, start, stop, pause, duration, interval, getPhase, minLatency };
+
+function createClock(
+  getTime,
+  callback, // called slightly before each cycle
+  duration = 0.05, // duration of each cycle
+  interval = 0.1, // interval between callbacks
+  overlap = 0.1, // overlap between callbacks
+) {
+  let tick = 0; // counts callbacks
+  let phase = 0; // next callback time
+  let precision = 10 ** 4; // used to round phase
+  let minLatency = 0.01;
+  const setDuration = (setter) => (duration = setter(duration));
+  overlap = overlap || interval / 2;
+  const onTick = () => {
+    const t = getTime();
+    const lookahead = t + interval + overlap; // the time window for this tick
+    if (phase === 0) {
+      phase = t + minLatency;
+    }
+    // callback as long as we're inside the lookahead
+    while (phase < lookahead) {
+      phase = Math.round(phase * precision) / precision;
+      phase >= t && callback(phase, duration, tick);
+      phase < t && console.log('TOO LATE', phase); // what if latency is added from outside?
+      phase += duration; // increment phase by duration
+      tick++;
+    }
   };
+  let intervalID;
+  const start = () => {
+    clear(); // just in case start was called more than once
+    onTick();
+    intervalID = setInterval(onTick, interval * 1000);
+  };
+  const clear = () => intervalID !== undefined && clearInterval(intervalID);
+  const pause = () => clear();
+  const stop = () => {
+    tick = 0;
+    phase = 0;
+    clear();
+  };
+  const getPhase = () => phase;
+  // setCallback
+  return { setDuration, start, stop, pause, duration, interval, getPhase, minLatency };
 }
+export default createClock;