diff --git a/src/Analyzers/BodyAnalyzer.php b/src/Analyzers/BodyAnalyzer.php
index fe46e5e..2e5e66e 100644
--- a/src/Analyzers/BodyAnalyzer.php
+++ b/src/Analyzers/BodyAnalyzer.php
@@ -175,11 +175,17 @@ protected function run()
         $version = $this->version;
 
         $players = $this->get(PlayerMetaAnalyzer::class);
+
+        // The player number is used for chat messages.
+        $playersByNumber = [];
+        // The player index is used for game actions.
         $playersByIndex = [];
         foreach ($players as $player) {
+            $playersByNumber[$player->number] = $player;
             $playersByIndex[$player->index] = $player;
         }
-        $this->playersByIndex = $playersByIndex;
+
+        $this->playersByNumber = $playersByNumber;
 
         $size = strlen($this->body);
         $this->position = 0;
@@ -392,10 +398,12 @@ private function processChatMessage()
             if (substr($chat, 3, 2) == '--' && substr($chat, -2) == '--') {
                 // Skip messages like "--Warning: You are under attack... --"
                 return;
-            } else if (!empty($this->playersByIndex[$chat[2]])) {
-                $player = $this->playersByIndex[$chat[2]];
+            } else if (!empty($this->playersByNumber[$chat[2]])) {
+                $player = $this->playersByNumber[$chat[2]];
             } else {
-                // This player left before the game started.
+                // Shouldn't happen, but we'll let the ChatMessage factory
+                // create a fake player for this message.
+                // TODO that auto-create behaviour is probably not desirable…
                 $player = null;
             }
             $this->chatMessages[] = ChatMessage::create(
diff --git a/src/Analyzers/PlayerMetaAnalyzer.php b/src/Analyzers/PlayerMetaAnalyzer.php
index 1bce41b..4b52eea 100644
--- a/src/Analyzers/PlayerMetaAnalyzer.php
+++ b/src/Analyzers/PlayerMetaAnalyzer.php
@@ -27,7 +27,7 @@ protected function run()
 
         $players = [];
         for ($i = 0; $i <= 8; $i += 1) {
-            $player = $this->readPlayerMeta();
+            $player = $this->readPlayerMeta($i);
             if ($player->humanRaw === 0 || $player->humanRaw === 1) {
                 continue;
             }
@@ -51,9 +51,10 @@ protected function run()
      *
      * @return \RecAnalyst\Model\Player
      */
-    protected function readPlayerMeta()
+    protected function readPlayerMeta($i)
     {
         $player = new Player($this->rec);
+        $player->number = $i;
         $player->index = $this->readHeader('l', 4);
         $human = $this->readHeader('l', 4);
         $length = $this->readHeader('L', 4);
diff --git a/src/Model/Player.php b/src/Model/Player.php
index 3a3b041..d650ebe 100644
--- a/src/Model/Player.php
+++ b/src/Model/Player.php
@@ -35,6 +35,17 @@ class Player
      */
     public $index = -1;
 
+    /**
+     * The player number. This is different from the index. The player number
+     * is always a sequential unique ID. The player index is the same for
+     * multiple players in the case of a co-op game.
+     *
+     * @var int
+     * @internal Might be public later, but should just be used internally for
+     *           now.
+     */
+    public $number = -1;
+
     /**
      * Defines if the player is a human.
      *