diff --git a/.changeset/gorgeous-eyes-cheer.md b/.changeset/gorgeous-eyes-cheer.md
new file mode 100644
index 00000000..cc85c9d5
--- /dev/null
+++ b/.changeset/gorgeous-eyes-cheer.md
@@ -0,0 +1,5 @@
+---
+'preact-render-to-string': patch
+---
+
+Ensure `cellPadding`, `cellSpacing`, and `useMap` are serialized to lower case
diff --git a/src/lib/util.js b/src/lib/util.js
index 12b5a4cc..fd86e5d6 100644
--- a/src/lib/util.js
+++ b/src/lib/util.js
@@ -1,7 +1,7 @@
 export const VOID_ELEMENTS = /^(?:area|base|br|col|embed|hr|img|input|link|meta|param|source|track|wbr)$/;
 export const UNSAFE_NAME = /[\s\n\\/='"\0<>]/;
 export const NAMESPACE_REPLACE_REGEX = /^(xlink|xmlns|xml)([A-Z])/;
-export const HTML_LOWER_CASE = /^accessK|^auto[A-Z]|^ch|^col|cont|cross|dateT|encT|form[A-Z]|frame|hrefL|inputM|maxL|minL|noV|playsI|popoverT|readO|rowS|spellC|src[A-Z]|tabI|item[A-Z]/;
+export const HTML_LOWER_CASE = /^accessK|^auto[A-Z]|^cell|^ch|^col|cont|cross|dateT|encT|form[A-Z]|frame|hrefL|inputM|maxL|minL|noV|playsI|popoverT|readO|rowS|spellC|src[A-Z]|tabI|useM|item[A-Z]/;
 export const SVG_CAMEL_CASE = /^ac|^ali|arabic|basel|cap|clipPath$|clipRule$|color|dominant|enable|fill|flood|font|glyph[^R]|horiz|image|letter|lighting|marker[^WUH]|overline|panose|pointe|paint|rendering|shape|stop|strikethrough|stroke|text[^L]|transform|underline|unicode|units|^v[^i]|^w|^xH/;
 
 // DOM properties that should NOT have "px" added when numeric
diff --git a/test/utils.js b/test/utils.js
index cadfb55a..068a1149 100644
--- a/test/utils.js
+++ b/test/utils.js
@@ -297,8 +297,8 @@ export const htmlAttributes = {
 	autoFocus: 'autofocus',
 	autoPlay: 'autoplay',
 	capture: 'capture',
-	cellPadding: 'cellPadding',
-	cellSpacing: 'cellSpacing',
+	cellPadding: 'cellpadding',
+	cellSpacing: 'cellspacing',
 	charSet: 'charset',
 	challenge: 'challenge',
 	checked: 'checked',
@@ -414,7 +414,7 @@ export const htmlAttributes = {
 	target: 'target',
 	title: 'title',
 	type: 'type',
-	useMap: 'useMap',
+	useMap: 'usemap',
 	value: 'value',
 	volume: 'volume',
 	width: 'width',