diff --git a/src/vs/editor/node/textMate/TMSyntax.ts b/src/vs/editor/node/textMate/TMSyntax.ts
index 9682c08a15b07..3cd7a4cd68fe4 100644
--- a/src/vs/editor/node/textMate/TMSyntax.ts
+++ b/src/vs/editor/node/textMate/TMSyntax.ts
@@ -88,7 +88,9 @@ export class TMScopeRegistry {
 				// no scopes registered
 				return null;
 			}
-			this._cachedScopesRegex = new RegExp(`^((${escapedScopes.join(')|(')}))`, '');
+			escapedScopes.sort();
+			escapedScopes.reverse();
+			this._cachedScopesRegex = new RegExp(`^((${escapedScopes.join(')|(')}))($|\\.)`, '');
 		}
 		return this._cachedScopesRegex;
 	}
diff --git a/src/vs/editor/test/node/textMate/TMSyntax.test.ts b/src/vs/editor/test/node/textMate/TMSyntax.test.ts
index f6e0499ca1bea..eccbcfd0b85a4 100644
--- a/src/vs/editor/test/node/textMate/TMSyntax.test.ts
+++ b/src/vs/editor/test/node/textMate/TMSyntax.test.ts
@@ -37,6 +37,7 @@ suite('TextMate.TMScopeRegistry', () => {
 		assert.equal(manager.scopeToLanguage('source.html'), null);
 
 		manager.register('html', 'source.html', null);
+		manager.register('c', 'source.c', null);
 		manager.register('css', 'source.css', null);
 		manager.register('javascript', 'source.js', null);
 		manager.register('python', 'source.python', null);
@@ -46,6 +47,7 @@ suite('TextMate.TMScopeRegistry', () => {
 		// exact matches
 		assert.equal(manager.scopeToLanguage('source.html'), 'html');
 		assert.equal(manager.scopeToLanguage('source.css'), 'css');
+		assert.equal(manager.scopeToLanguage('source.c'), 'c');
 		assert.equal(manager.scopeToLanguage('source.js'), 'javascript');
 		assert.equal(manager.scopeToLanguage('source.python'), 'python');
 		assert.equal(manager.scopeToLanguage('source.smarty'), 'smarty');
@@ -58,10 +60,12 @@ suite('TextMate.TMScopeRegistry', () => {
 
 		// misses
 		assert.equal(manager.scopeToLanguage('source.ts'), null);
+		assert.equal(manager.scopeToLanguage('source.csss'), null);
 		assert.equal(manager.scopeToLanguage('source.baz'), null);
 		assert.equal(manager.scopeToLanguage('asource.css'), null);
 		assert.equal(manager.scopeToLanguage('a.source.css'), null);
 		assert.equal(manager.scopeToLanguage('source_css'), null);
+		assert.equal(manager.scopeToLanguage('punctuation.definition.tag.html'), null);
 	});
 
 });