diff --git a/packages/happy-dom/src/query-selector/SelectorParser.ts b/packages/happy-dom/src/query-selector/SelectorParser.ts
index 5f5d05909..d293b8f12 100644
--- a/packages/happy-dom/src/query-selector/SelectorParser.ts
+++ b/packages/happy-dom/src/query-selector/SelectorParser.ts
@@ -25,7 +25,7 @@ import ISelectorPseudo from './ISelectorPseudo.js';
  * Group 17: Combinator.
  */
 const SELECTOR_REGEXP =
-	/(\*)|([a-zA-Z0-9-]+)|#((?:[a-zA-Z0-9-_]|\\.)+)|\.((?:[a-zA-Z0-9-_]|\\.)+)|\[([a-zA-Z0-9-_]+)\]|\[([a-zA-Z0-9-_]+) *([~|^$*]{0,1}) *= *["']{1}([^"']*)["']{1} *(s|i){0,1}\]|\[([a-zA-Z0-9-_]+) *([~|^$*]{0,1}) *= *([^\]]*)\]|:([a-zA-Z-]+) *\(([^)]+)\)|:([a-zA-Z-]+)|::([a-zA-Z-]+)|([ ,+>]*)/g;
+	/(\*)|([a-zA-Z0-9-]+)|#((?:[a-zA-Z0-9-_]|\\.)+)|\.((?:[a-zA-Z0-9-_]|\\.)+)|\[([a-zA-Z0-9-_]+)\]|\[([a-zA-Z0-9-_]+) *([~|^$*]{0,1}) *= *["']{1}([^"']*)["']{1} *(s|i){0,1}\]|\[([a-zA-Z0-9-_]+) *([~|^$*]{0,1}) *= *([^\]]*)\]|:([a-zA-Z-]+) *\(([^)]+\)?)\)|:([a-zA-Z-]+)|::([a-zA-Z-]+)|([ ,+>]*)/g;
 
 /**
  * Escaped Character RegExp.
diff --git a/packages/happy-dom/test/query-selector/QuerySelector.test.ts b/packages/happy-dom/test/query-selector/QuerySelector.test.ts
index caa3d1445..a26c5dace 100644
--- a/packages/happy-dom/test/query-selector/QuerySelector.test.ts
+++ b/packages/happy-dom/test/query-selector/QuerySelector.test.ts
@@ -1158,5 +1158,16 @@ describe('QuerySelector', () => {
 				"Failed to execute 'querySelector' on 'HTMLElement': '#1' is not a valid selector."
 			);
 		});
+
+		it('Has support for passing pseudoseletors inside :not', () => {
+			const div = document.createElement('div');
+			const child = document.createElement('div');
+			const child2 = document.createElement('div');
+
+			div.appendChild(child);
+			div.appendChild(child2);
+
+			expect(div.querySelector(':not(:nth-child(1))')).toBe(child2);
+		});
 	});
 });