diff --git a/src/CssLint/Referential/NonStandard/PropertiesReferential.php b/src/CssLint/Referential/NonStandard/PropertiesReferential.php
index 1ed0a2b..44f6d7a 100644
--- a/src/CssLint/Referential/NonStandard/PropertiesReferential.php
+++ b/src/CssLint/Referential/NonStandard/PropertiesReferential.php
@@ -130,6 +130,23 @@ class PropertiesReferential extends AbstractReferential
         'column-rule-outset' => true,
         'column-wrap' => true,
         'continue' => true,
+        'corner' => true,
+        'corner-block-end' => true,
+        'corner-block-start' => true,
+        'corner-bottom' => true,
+        'corner-bottom-left' => true,
+        'corner-bottom-right' => true,
+        'corner-end-end' => true,
+        'corner-end-start' => true,
+        'corner-inline-end' => true,
+        'corner-inline-start' => true,
+        'corner-left' => true,
+        'corner-right' => true,
+        'corner-start-end' => true,
+        'corner-start-start' => true,
+        'corner-top' => true,
+        'corner-top-left' => true,
+        'corner-top-right' => true,
         'cue' => true,
         'cue-after' => true,
         'cue-before' => true,