diff --git a/src/languages/stan.js b/src/languages/stan.js
index a95ab8f3eb..b0ec9fb050 100644
--- a/src/languages/stan.js
+++ b/src/languages/stan.js
@@ -7,6 +7,7 @@ Category: scientific
 */
 
 export default function(hljs) {
+  const regex = hljs.regex;
   // variable names cannot conflict with block identifiers
   const BLOCKS = [
     'functions',
@@ -29,7 +30,7 @@ export default function(hljs) {
     'return'
   ];
 
-  const VAR_TYPES = [
+  const TYPES = [
     'array',
     'complex',
     'int',
@@ -377,7 +378,6 @@ export default function(hljs) {
     className: 'meta',
     begin: /#include\b/,
     end: /$/,
-    relevance: 0, // relevance comes from keywords
     contains: [
       {
         match: /[a-z][a-z-.]+/,
@@ -387,19 +387,12 @@ export default function(hljs) {
     ]
   };
 
-  const numberRegex = new RegExp([
-    // Comes from @RunDevelopment accessed 11/29/2021 at
-    // https://github.com/PrismJS/prism/blob/c53ad2e65b7193ab4f03a1797506a54bbb33d5a2/components/prism-stan.js#L56
-
-    // start of big noncapture group which
-    // 1. gets numbers that are by themselves
-    // 2. numbers that are separated by _
-    // 3. numbers that are separted by .
-    /(?:\b\d+(?:_\d+)*(?:\.(?:\d+(?:_\d+)*)?)?|\B\.\d+(?:_\d+)*)/,
-    // grabs scientific notation
-    // grabs complex numbers with i
-    /(?:[eE][+-]?\d+(?:_\d+)*)?i?(?!\w)/
-  ].map(function(r) { return r.source; }).join(''), 'i');
+  const RANGE_CONSTRAINTS = [
+    "lower",
+    "upper",
+    "offset",
+    "multiplier"
+  ];
 
   return {
     name: 'Stan',
@@ -407,7 +400,8 @@ export default function(hljs) {
     keywords: {
       $pattern: hljs.IDENT_RE,
       title: BLOCKS,
-      keyword: STATEMENTS.concat(VAR_TYPES),
+      type: TYPES,
+      keyword: STATEMENTS,
       built_in: FUNCTIONS
     },
     contains: [
@@ -421,28 +415,8 @@ export default function(hljs) {
         relevance: 0
       },
       {
-        // hack: in range constraints, lower must follow either , or <
-        // <upper = ..., lower = ...> or <lower = ...>
-        begin: /[<,]\s*lower\s*=/,
-        keywords: 'lower'
-      },
-      {
-        // hack: in range constraints, upper must follow either , or <
-        // <lower = ..., upper = ...> or <upper = ...>
-        begin: /[<,]\s*upper\s*=/,
-        keywords: 'upper'
-      },
-      {
-        // hack: in range constraints, upper must follow either , or <
-        // <multiplier = ..., offest = ...> or <offset = ...>
-        begin: /[<,]\s*offset\s*=/,
-        keywords: 'offset'
-      },
-      {
-        // hack: in range constraints, upper must follow either , or <
-        // <offset = ..., multiplier = ...> or <multiplier = ...>
-        begin: /[<,]\s*multiplier\s*=/,
-        keywords: 'multiplier'
+        begin: regex.concat(/[<,]\s*/, regex.either(...RANGE_CONSTRAINTS), /\s*=/),
+        keywords: RANGE_CONSTRAINTS
       },
       {
         className: 'keyword',
@@ -485,17 +459,25 @@ export default function(hljs) {
       },
       {
         className: 'number',
-        variants: [
-          { begin: numberRegex },
-          { begin: /\.\d+(?:[eE][+-]?\d+)?\b/ }
-        ],
+        begin: regex.concat(
+          // Comes from @RunDevelopment accessed 11/29/2021 at
+          // https://github.com/PrismJS/prism/blob/c53ad2e65b7193ab4f03a1797506a54bbb33d5a2/components/prism-stan.js#L56
+
+          // start of big noncapture group which
+          // 1. gets numbers that are by themselves
+          // 2. numbers that are separated by _
+          // 3. numbers that are separted by .
+          /(?:\b\d+(?:_\d+)*(?:\.(?:\d+(?:_\d+)*)?)?|\B\.\d+(?:_\d+)*)/,
+          // grabs scientific notation
+          // grabs complex numbers with i
+          /(?:[eE][+-]?\d+(?:_\d+)*)?i?(?!\w)/
+        ),
         relevance: 0
       },
       {
         className: 'string',
         begin: '"',
-        end: '"',
-        relevance: 0
+        end: '"'
       }
     ]
   };
diff --git a/test/markup/stan/default.expect.txt b/test/markup/stan/default.expect.txt
index 1a722a197f..39fc99e4f5 100644
--- a/test/markup/stan/default.expect.txt
+++ b/test/markup/stan/default.expect.txt
@@ -2,20 +2,20 @@
   <span class="hljs-meta">#include <span class="hljs-string">normal</span>_<span class="hljs-string">copula.stanfunctions</span></span>
 }
 <span class="hljs-title">data</span> {
-  <span class="hljs-keyword">int</span>&lt;<span class="hljs-keyword">lower</span>=<span class="hljs-number">0</span>&gt; N;
-  <span class="hljs-keyword">int</span> K;
-  <span class="hljs-keyword">matrix</span>[N, K] x;
+  <span class="hljs-type">int</span>&lt;<span class="hljs-keyword">lower</span>=<span class="hljs-number">0</span>&gt; N;
+  <span class="hljs-type">int</span> K;
+  <span class="hljs-type">matrix</span>[N, K] x;
 }
 <span class="hljs-title">transformed</span> <span class="hljs-title">data</span> {
-    <span class="hljs-keyword">complex</span> zi = <span class="hljs-number">1</span>+<span class="hljs-number">3.14i</span>;
+    <span class="hljs-type">complex</span> zi = <span class="hljs-number">1</span>+<span class="hljs-number">3.14i</span>;
     zi = zi * <span class="hljs-number">0i</span>;
-    <span class="hljs-keyword">complex</span> yi = <span class="hljs-built_in">to_complex</span>(<span class="hljs-number">0</span>, <span class="hljs-number">1.1</span>) + <span class="hljs-built_in">to_complex</span>(<span class="hljs-number">0.0</span>, <span class="hljs-number">2.2</span>) + <span class="hljs-built_in">to_complex</span>();
-    <span class="hljs-keyword">real</span> x = <span class="hljs-built_in">get_real</span>(<span class="hljs-number">3i</span> - <span class="hljs-number">40e-3i</span> + <span class="hljs-number">1e10i</span>);
+    <span class="hljs-type">complex</span> yi = <span class="hljs-built_in">to_complex</span>(<span class="hljs-number">0</span>, <span class="hljs-number">1.1</span>) + <span class="hljs-built_in">to_complex</span>(<span class="hljs-number">0.0</span>, <span class="hljs-number">2.2</span>) + <span class="hljs-built_in">to_complex</span>();
+    <span class="hljs-type">real</span> x = <span class="hljs-built_in">get_real</span>(<span class="hljs-number">3i</span> - <span class="hljs-number">40e-3i</span> + <span class="hljs-number">1e10i</span>);
 }›
 <span class="hljs-title">parameters</span> {
-  <span class="hljs-keyword">array</span>[K - <span class="hljs-number">1</span>] <span class="hljs-keyword">real</span> mu;
-  <span class="hljs-keyword">array</span>[K + <span class="hljs-number">1</span>] <span class="hljs-keyword">real</span>&lt;<span class="hljs-keyword">lower</span>=<span class="hljs-number">0</span>&gt; sigma;
-  <span class="hljs-keyword">cholesky_factor_corr</span>[K] L;
+  <span class="hljs-type">array</span>[K - <span class="hljs-number">1</span>] <span class="hljs-type">real</span> mu;
+  <span class="hljs-type">array</span>[K + <span class="hljs-number">1</span>] <span class="hljs-type">real</span>&lt;<span class="hljs-keyword">lower</span>=<span class="hljs-number">0</span>&gt; sigma;
+  <span class="hljs-type">cholesky_factor_corr</span>[K] L;
 }
 <span class="hljs-title">model</span> {
   <span class="hljs-keyword">target </span>+= <span class="hljs-built_in">normal_lpdf</span>(x[ : , <span class="hljs-number">1</span>] | mu[<span class="hljs-number">1</span>], sigma[<span class="hljs-number">1</span>]);
@@ -24,7 +24,7 @@
   <span class="hljs-keyword">target </span>+= <span class="hljs-built_in">weibull_lpdf</span>(x[ : , <span class="hljs-number">4</span>] | sigma[<span class="hljs-number">4</span>], sigma[<span class="hljs-number">5</span>]);
   
   {
-    <span class="hljs-keyword">matrix</span>[K, N] y;
+    <span class="hljs-type">matrix</span>[K, N] y;
     <span class="hljs-keyword">for</span> (n <span class="hljs-keyword">in</span> <span class="hljs-number">1</span> : N) {
       y[<span class="hljs-number">1</span>, n] = <span class="hljs-built_in">inv_Phi</span>(<span class="hljs-built_in">normal_cdf</span>(x[n, <span class="hljs-number">1</span>] | mu[<span class="hljs-number">1</span>], sigma[<span class="hljs-number">1</span>]));
       y[<span class="hljs-number">2</span>, n] = <span class="hljs-built_in">inv_Phi</span>(<span class="hljs-built_in">gumbel_cdf</span>(x[n, <span class="hljs-number">2</span>] | mu[<span class="hljs-number">2</span>], sigma[<span class="hljs-number">2</span>]));
@@ -36,5 +36,5 @@
   }
 }
 <span class="hljs-title">generated</span> <span class="hljs-title">quantities</span> {
-  <span class="hljs-keyword">matrix</span>[K, K] Sigma = <span class="hljs-built_in">multiply_lower_tri_self_transpose</span>(L);
+  <span class="hljs-type">matrix</span>[K, K] Sigma = <span class="hljs-built_in">multiply_lower_tri_self_transpose</span>(L);
 }
\ No newline at end of file