diff --git a/src/__fixtures__/tests.ts b/src/__fixtures__/tests.ts
index 625d984b..026fea4b 100644
--- a/src/__fixtures__/tests.ts
+++ b/src/__fixtures__/tests.ts
@@ -458,6 +458,27 @@ export const tests: [
         ],
         "pseudo selector with data",
     ],
+    [
+        ":where(a)",
+        [
+            [
+                {
+                    type: "pseudo",
+                    name: "where",
+                    data: [
+                        [
+                            {
+                                type: "tag",
+                                namespace: null,
+                                name: "a",
+                            },
+                        ],
+                    ],
+                },
+            ],
+        ],
+        "pseudo selector with data",
+    ],
     [
         ':contains("(a((foo\\\\\\))))")',
         [
diff --git a/src/parse.ts b/src/parse.ts
index 118e8a59..07c53404 100644
--- a/src/parse.ts
+++ b/src/parse.ts
@@ -109,6 +109,7 @@ const unpackPseudos = new Set([
     "not",
     "matches",
     "is",
+    "where",
     "host",
     "host-context",
 ]);