diff --git a/lib/utils/__tests__/isStandardSyntaxRule.test.js b/lib/utils/__tests__/isStandardSyntaxRule.test.js
index 025ab14a04..d4379764ca 100644
--- a/lib/utils/__tests__/isStandardSyntaxRule.test.js
+++ b/lib/utils/__tests__/isStandardSyntaxRule.test.js
@@ -79,6 +79,9 @@ describe('isStandardSyntaxRule', () => {
 	it('less guarded namespaces', () => {
 		expect(isStandardSyntaxRule(lessNode('#namespace when (@mode=huge) {}'))).toBeFalsy();
 	});
+	it('less parametric mixins', () => {
+		expect(isStandardSyntaxRule(lessNode('.mixin (@variable: 5) {}'))).toBeFalsy();
+	});
 	it('mixin guards', () => {
 		expect(
 			isStandardSyntaxRule(lessNode('.mixin (@variable) when (@variable = 10px) {}')),
diff --git a/lib/utils/isStandardSyntaxRule.js b/lib/utils/isStandardSyntaxRule.js
index bca92da849..076729ff8f 100644
--- a/lib/utils/isStandardSyntaxRule.js
+++ b/lib/utils/isStandardSyntaxRule.js
@@ -60,6 +60,11 @@ module.exports = function (rule) {
 		return false;
 	}
 
+	// Less Parametric mixins (e.g. .mixin(@variable: x) {})
+	if (/\(@.*\)$/.test(selector)) {
+		return false;
+	}
+
 	// Ignore Scss nested properties
 	if (selector.endsWith(':')) {
 		return false;