diff --git a/cmd/anubis/js/proof-of-work.mjs b/cmd/anubis/js/proof-of-work.mjs
index 5a5f9f9..3125ae6 100644
--- a/cmd/anubis/js/proof-of-work.mjs
+++ b/cmd/anubis/js/proof-of-work.mjs
@@ -1,6 +1,6 @@
 // https://dev.to/ratmd/simple-proof-of-work-in-javascript-3kgm
 
-export function process(data, difficulty = 5, threads = navigator.hardwareConcurrency) {
+export function process(data, difficulty = 5, threads = (navigator.hardwareConcurrency || 1)) {
   return new Promise((resolve, reject) => {
     let webWorkerURL = URL.createObjectURL(new Blob([
       '(', processTask(), ')()'
diff --git a/cmd/anubis/static/js/main.mjs b/cmd/anubis/static/js/main.mjs
index ffa524b..d1e1b86 100644
--- a/cmd/anubis/static/js/main.mjs
+++ b/cmd/anubis/static/js/main.mjs
@@ -1,2 +1,2 @@
-(()=>{function m(n,s=5,e=navigator.hardwareConcurrency){return new Promise((t,l)=>{let a=URL.createObjectURL(new Blob(["(",g(),")()"],{type:"application/javascript"})),r=[];for(let d=0;d<e;d++){let i=new Worker(a);i.onmessage=c=>{r.forEach(u=>u.terminate()),i.terminate(),t(c.data)},i.onerror=c=>{i.terminate(),l()},i.postMessage({data:n,difficulty:s,nonce:d,threads:e}),r.push(i)}URL.revokeObjectURL(a)})}function g(){return function(){let n=e=>{let t=new TextEncoder().encode(e);return crypto.subtle.digest("SHA-256",t.buffer)};function s(e){return Array.from(e).map(t=>t.toString(16).padStart(2,"0")).join("")}addEventListener("message",async e=>{let t=e.data.data,l=e.data.difficulty,a,r=e.data.nonce,d=e.data.threads;for(;;){let i=await n(t+r),c=new Uint8Array(i),u=!0;for(let o=0;o<l;o++){let f=Math.floor(o/2),p=o%2;if((c[f]>>(p===0?4:0)&15)!==0){u=!1;break}}if(u){a=s(c),console.log(a);break}r+=d}postMessage({hash:a,data:t,difficulty:l,nonce:r})})}.toString()}var w=(n="",s={})=>{let e=new URL(n,window.location.href);return Object.entries(s).forEach(t=>{let[l,a]=t;e.searchParams.set(l,a)}),e.toString()},h=(n,s)=>w(`/.within.website/x/cmd/anubis/static/img/${n}.webp`,{cacheBuster:s});(async()=>{let n=document.getElementById("status"),s=document.getElementById("image"),e=document.getElementById("title"),t=document.getElementById("spinner"),l=JSON.parse(document.getElementById("anubis_version").textContent);n.innerHTML="Calculating...";let{challenge:a,difficulty:r}=await fetch("/.within.website/x/cmd/anubis/api/make-challenge",{method:"POST"}).then(o=>{if(!o.ok)throw new Error("Failed to fetch config");return o.json()}).catch(o=>{throw e.innerHTML="Oh no!",n.innerHTML=`Failed to fetch config: ${o.message}`,s.src=h("sad"),t.innerHTML="",t.style.display="none",o});n.innerHTML=`Calculating...<br/>Difficulty: ${r}`;let d=Date.now(),{hash:i,nonce:c}=await m(a,r),u=Date.now();console.log({hash:i,nonce:c}),e.innerHTML="Success!",n.innerHTML=`Done! Took ${u-d}ms, ${c} iterations`,s.src=h("happy",l),t.innerHTML="",t.style.display="none",setTimeout(()=>{let o=window.location.href;window.location.href=w("/.within.website/x/cmd/anubis/api/pass-challenge",{response:i,nonce:c,redir:o,elapsedTime:u-d})},250)})();})();
+(()=>{function m(n,s=5,e=(navigator.hardwareConcurrency||1)){return new Promise((t,l)=>{let a=URL.createObjectURL(new Blob(["(",g(),")()"],{type:"application/javascript"})),r=[];for(let d=0;d<e;d++){let i=new Worker(a);i.onmessage=c=>{r.forEach(u=>u.terminate()),i.terminate(),t(c.data)},i.onerror=c=>{i.terminate(),l()},i.postMessage({data:n,difficulty:s,nonce:d,threads:e}),r.push(i)}URL.revokeObjectURL(a)})}function g(){return function(){let n=e=>{let t=new TextEncoder().encode(e);return crypto.subtle.digest("SHA-256",t.buffer)};function s(e){return Array.from(e).map(t=>t.toString(16).padStart(2,"0")).join("")}addEventListener("message",async e=>{let t=e.data.data,l=e.data.difficulty,a,r=e.data.nonce,d=e.data.threads;for(;;){let i=await n(t+r),c=new Uint8Array(i),u=!0;for(let o=0;o<l;o++){let f=Math.floor(o/2),p=o%2;if((c[f]>>(p===0?4:0)&15)!==0){u=!1;break}}if(u){a=s(c),console.log(a);break}r+=d}postMessage({hash:a,data:t,difficulty:l,nonce:r})})}.toString()}var w=(n="",s={})=>{let e=new URL(n,window.location.href);return Object.entries(s).forEach(t=>{let[l,a]=t;e.searchParams.set(l,a)}),e.toString()},h=(n,s)=>w(`/.within.website/x/cmd/anubis/static/img/${n}.webp`,{cacheBuster:s});(async()=>{let n=document.getElementById("status"),s=document.getElementById("image"),e=document.getElementById("title"),t=document.getElementById("spinner"),l=JSON.parse(document.getElementById("anubis_version").textContent);n.innerHTML="Calculating...";let{challenge:a,difficulty:r}=await fetch("/.within.website/x/cmd/anubis/api/make-challenge",{method:"POST"}).then(o=>{if(!o.ok)throw new Error("Failed to fetch config");return o.json()}).catch(o=>{throw e.innerHTML="Oh no!",n.innerHTML=`Failed to fetch config: ${o.message}`,s.src=h("sad"),t.innerHTML="",t.style.display="none",o});n.innerHTML=`Calculating...<br/>Difficulty: ${r}`;let d=Date.now(),{hash:i,nonce:c}=await m(a,r),u=Date.now();console.log({hash:i,nonce:c}),e.innerHTML="Success!",n.innerHTML=`Done! Took ${u-d}ms, ${c} iterations`,s.src=h("happy",l),t.innerHTML="",t.style.display="none",setTimeout(()=>{let o=window.location.href;window.location.href=w("/.within.website/x/cmd/anubis/api/pass-challenge",{response:i,nonce:c,redir:o,elapsedTime:u-d})},250)})();})();
 //# sourceMappingURL=main.mjs.map
diff --git a/docs/docs/CHANGELOG.md b/docs/docs/CHANGELOG.md
index 651b5e5..e9ce9eb 100644
--- a/docs/docs/CHANGELOG.md
+++ b/docs/docs/CHANGELOG.md
@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Don't duplicate work across multiple threads [#36](https://github.com/TecharoHQ/anubis/pull/36)
 - Documentation has been moved to https://anubis.techaro.lol/ with sources in docs/
 - Removed several visible AI artifacts (e.g., 6 fingers) [#37](https://github.com/TecharoHQ/anubis/pull/37)
+- Fixed hang when navigator.hardwareConcurrency is undefined
 
 ## 1.13.0