diff --git a/.phan/baseline.php b/.phan/baseline.php
new file mode 100644
index 0000000..383541a
--- /dev/null
+++ b/.phan/baseline.php
@@ -0,0 +1,56 @@
+<?php
+
+return [
+    'file_suppressions' => [
+        'src/ActivityApi.php' => ['PhanUnextractableAnnotation'],
+        'src/BlogsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/CamerasApi.php' => ['PhanUnextractableAnnotation'],
+        'src/CollectionsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/CommonsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/ContactsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/FavoritesApi.php' => ['PhanUnextractableAnnotation'],
+        'src/GalleriesApi.php' => ['PhanTypeMismatchDefault', 'PhanUnextractableAnnotation'],
+        'src/GroupsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/GroupsDiscussRepliesApi.php' => ['PhanUnextractableAnnotation'],
+        'src/GroupsDiscussTopicsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/GroupsMembersApi.php' => ['PhanUnextractableAnnotation'],
+        'src/GroupsPoolsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/InterestingnessApi.php' => ['PhanUnextractableAnnotation'],
+        'src/MachinetagsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/Oauth/PhpFlickrService.php' => [
+            'PhanUndeclaredClass', 'PhanUndeclaredClassMethod', 'PhanUndeclaredExtendedClass',
+            'PhanUndeclaredMethod', 'PhanUndeclaredProperty', 'PhanUndeclaredTypeParameter',
+            'PhanUnreferencedUseNormal'
+        ],
+        'src/PandaApi.php' => ['PhanUnextractableAnnotation'],
+        'src/PeopleApi.php' => ['PhanUnextractableAnnotation'],
+        'src/PhotosApi.php' => ['PhanTypeMismatchDefault', 'PhanTypeMismatchForeach', 'PhanUnextractableAnnotation'],
+        'src/PhotosCommentsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/PhotosGeoApi.php' => ['PhanUnextractableAnnotation'],
+        'src/PhotosNotesApi.php' => ['PhanUnextractableAnnotation'],
+        'src/PhotosPeopleApi.php' => ['PhanUnextractableAnnotation'],
+        'src/PhotosSuggestionsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/PhotosTransformApi.php' => ['PhanUnextractableAnnotation'],
+        'src/PhotosUploadApi.php' => ['PhanUnextractableAnnotation'],
+        'src/PhotosetsCommentsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/PhpFlickr.php' => [
+            'PhanInvalidCommentForDeclarationType', 'PhanTypeConversionFromArray', 'PhanTypeMismatchArgumentInternal',
+            'PhanTypeMismatchProperty', 'PhanTypeMismatchReturnProbablyReal', 'PhanUndeclaredClassInstanceof',
+            'PhanUndeclaredClassMethod', 'PhanUndeclaredMethod', 'PhanUndeclaredTypeParameter',
+            'PhanUndeclaredTypeProperty', 'PhanUndeclaredTypeReturnType', 'PhanUnreferencedUseNormal'
+        ],
+        'src/PlacesApi.php' => ['PhanUnextractableAnnotation'],
+        'src/PrefsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/PushApi.php' => ['PhanUnextractableAnnotation'],
+        'src/ReflectionApi.php' => ['PhanUnextractableAnnotation'],
+        'src/StatsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/TagsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/TestApi.php' => ['PhanUndeclaredClassCatch'],
+        'src/TestimonialsApi.php' => ['PhanUnextractableAnnotation'],
+        'src/Uploader.php' => [
+            'PhanUndeclaredClassMethod', 'PhanUndeclaredProperty',
+            'PhanUndeclaredTypeThrowsType', 'PhanUnreferencedUseNormal'
+        ],
+        'src/Util.php' => ['PhanParamSuspiciousOrder'],
+    ],
+];
diff --git a/.phan/config.php b/.phan/config.php
new file mode 100644
index 0000000..74a9cab
--- /dev/null
+++ b/.phan/config.php
@@ -0,0 +1,11 @@
+<?php
+
+return [
+    'directory_list' => [
+        'src',
+    ],
+    'exclude_file_regex' => '@^vendor/.*/(tests?|Tests?)/@',
+    'exclude_analysis_directory_list' => [
+        'vendor/'
+    ],
+];
diff --git a/composer.json b/composer.json
index 06e7252..2aa251b 100644
--- a/composer.json
+++ b/composer.json
@@ -27,14 +27,17 @@
 		"mediawiki/minus-x": "^0.3 || ^1.0",
 		"phpunit/phpunit": "^9.5",
 		"tedivm/stash": "^0.17.1",
-		"php-parallel-lint/php-parallel-lint": "^1.3"
+		"php-parallel-lint/php-parallel-lint": "^1.3",
+		"phan/phan": "^5.4"
 	},
 	"scripts": {
+		"phan": "phan --allow-polyfill-parser --load-baseline .phan/baseline.php",
 		"test": [
 			"composer validate",
 			"parallel-lint . --exclude node_modules --exclude vendor",
 			"minus-x check . -q",
 			"phpcs -sp",
+			"@phan",
 			"phpunit",
 			"git status | grep 'nothing to commit, working tree clean'"
 		]
diff --git a/src/PhpFlickr.php b/src/PhpFlickr.php
index a6f9c0f..a532e01 100644
--- a/src/PhpFlickr.php
+++ b/src/PhpFlickr.php
@@ -104,7 +104,7 @@ public function setCacheDefaultExpiry($time)
 
     /**
      * Get a cached request.
-     * @param string[] Array of request parameters ('api_sig' will be discarded).
+     * @param string[] $request Array of request parameters ('api_sig' will be discarded).
      * @return string[]
      */
     public function getCached($request)
diff --git a/src/ProfileApi.php b/src/ProfileApi.php
index 9d14271..7066432 100644
--- a/src/ProfileApi.php
+++ b/src/ProfileApi.php
@@ -11,7 +11,7 @@ class ProfileApi extends ApiMethodGroup
      *
      * @link https://www.flickr.com/services/api/flickr.profile.getProfile.html
      * @param string $userId The NSID of the user to fetch profile information for.
-     * @return
+     * @return array
      */
     public function getProfile($userId)
     {
diff --git a/src/Util.php b/src/Util.php
index de96a4c..1a7ed2c 100644
--- a/src/Util.php
+++ b/src/Util.php
@@ -42,7 +42,7 @@ public static function base58encode($num)
     /**
      * Decode a photo ID from Flickr's short-URL base-58 system.
      * @link https://www.flickr.com/groups/api/discuss/72157616713786392/
-     * @param int $num
+     * @param string $num
      * @return bool|int
      */
     public static function base58decode($num)
diff --git a/tests/ApiMethodGroup/PhotosApiTest.php b/tests/ApiMethodGroup/PhotosApiTest.php
index 6b86535..795c5ed 100644
--- a/tests/ApiMethodGroup/PhotosApiTest.php
+++ b/tests/ApiMethodGroup/PhotosApiTest.php
@@ -76,6 +76,9 @@ public function testSetTags()
 
         $photoInfo = $flickr->photos()->getInfo($testPhotoId);
         static::assertCount(3, $photoInfo['tags']['tag']);
+
+        // Clean up.
+        $flickr->photos()->delete($testPhotoId);
     }
 
     public function testSearch()