diff --git a/functionMap.php b/functionMap.php
index 91f51e5..07b3675 100644
--- a/functionMap.php
+++ b/functionMap.php
@@ -173,7 +173,7 @@
     'is_email' => [null, 'deprecated' => 'false'],
     'is_new_day' => ['0|1'],
     'is_term' => ["(\$term is 0 ? 0 : (\$term is '' ? null : (\$taxonomy is '' ? string|null : array{term_id: string, term_taxonomy_id: string}|null)))"],
-    'is_wp_error' => ['($thing is \WP_Error ? true : false)', '@phpstan-assert-if-true' => '\WP_Error $thing'],
+    'is_wp_error' => ['($thing is \WP_Error ? true : false)'],
     'load_plugin_textdomain' => [null, 'deprecated' => 'false'],
     'maybe_serialize' => ['(T is array|object|string ? string : T)', '@phpstan-template T' => 'of mixed', 'data' => 'T'],
     'mysql2date' => ["(\$format is 'G'|'U' ? int|false : string|false)"],
diff --git a/tests/data/assert/is-wp-error.php b/tests/data/assert/is-wp-error.php
deleted file mode 100644
index 09d5722..0000000
--- a/tests/data/assert/is-wp-error.php
+++ /dev/null
@@ -1,22 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace PhpStubs\WordPress\Core\Tests;
-
-use function is_wp_error;
-use function PHPStan\Testing\assertType;
-
-$stringOrWpError = Faker::union(Faker::string(), Faker::wpError());
-if (is_wp_error($stringOrWpError)) {
-    assertType('WP_Error', $stringOrWpError);
-    return;
-}
-assertType('string', $stringOrWpError);
-
-$stringOrWpError = Faker::union(Faker::string(), Faker::wpError());
-if (! is_wp_error($stringOrWpError)) {
-    assertType('string', $stringOrWpError);
-    return;
-}
-assertType('WP_Error', $stringOrWpError);
diff --git a/wordpress-stubs.php b/wordpress-stubs.php
index e32f64a..ee4cfe0 100644
--- a/wordpress-stubs.php
+++ b/wordpress-stubs.php
@@ -140554,7 +140554,6 @@ function wp_doing_cron()
      * @return bool Whether the variable is an instance of WP_Error.
      *
      * @phpstan-assert-if-true WP_Error $thing
-     * @phpstan-assert-if-true \WP_Error $thing
      * @phpstan-return ($thing is \WP_Error ? true : false)
      */
     function is_wp_error($thing)