diff --git a/src/Composer/Package/Comparer/Comparer.php b/src/Composer/Package/Comparer/Comparer.php
index be23bedf6..06ebf7daa 100644
--- a/src/Composer/Package/Comparer/Comparer.php
+++ b/src/Composer/Package/Comparer/Comparer.php
@@ -26,16 +26,32 @@ class Comparer
     /** @var array{changed?: string[], removed?: string[], added?: string[]} */
     private $changed;
 
+    /**
+     * @param string $source
+     *
+     * @return void
+     */
     public function setSource($source)
     {
         $this->source = $source;
     }
 
+    /**
+     * @param string $update
+     *
+     * @return void
+     */
     public function setUpdate($update)
     {
         $this->update = $update;
     }
 
+    /**
+     * @param bool $toString
+     * @param bool $explicated
+     *
+     * @return array{changed?: string[], removed?: string[], added?: string[]}|string|false false if no change, string only if $toString is true
+     */
     public function getChanged($toString = false, $explicated = false)
     {
         $changed = $this->changed;
@@ -62,6 +78,9 @@ class Comparer
         return $changed;
     }
 
+    /**
+     * @return void
+     */
     public function doCompare()
     {
         $source = array();
@@ -100,6 +119,12 @@ class Comparer
         }
     }
 
+    /**
+     * @param string $dir
+     * @param mixed $array
+     *
+     * @return array<string, array<string, string|false>>|false
+     */
     private function doTree($dir, &$array)
     {
         if ($dh = opendir($dir)) {