diff --git a/lib/rules/selector-type-no-unknown/__tests__/index.js b/lib/rules/selector-type-no-unknown/__tests__/index.js
index 88b415526d..642a7c2573 100644
--- a/lib/rules/selector-type-no-unknown/__tests__/index.js
+++ b/lib/rules/selector-type-no-unknown/__tests__/index.js
@@ -85,6 +85,10 @@ testRule(rule, {
 			code: 'circle {}',
 			description: 'svg tags',
 		},
+		{
+			code: 'foreignObject {}',
+			description: 'case-sensitive svg tags',
+		},
 		{
 			code: '@media keyframes { 0.0% {} 49.1% {} 100% {} }',
 			description: 'standard usage of keyframe selectors',
diff --git a/lib/rules/selector-type-no-unknown/index.js b/lib/rules/selector-type-no-unknown/index.js
index af9f8f94b0..592725ec39 100644
--- a/lib/rules/selector-type-no-unknown/index.js
+++ b/lib/rules/selector-type-no-unknown/index.js
@@ -87,7 +87,8 @@ const rule = function(actual, options) {
 
 					if (
 						htmlTags.includes(tagNameLowerCase) ||
-						svgTags.includes(tagNameLowerCase) ||
+						// SVG tags are case-sensitive
+						svgTags.includes(tagName) ||
 						keywordSets.nonStandardHtmlTags.has(tagNameLowerCase) ||
 						mathMLTags.includes(tagNameLowerCase)
 					) {