diff --git a/webseite/classes/SubjectData.php b/webseite/classes/SubjectData.php
index 180df3d..7f79d4f 100644
--- a/webseite/classes/SubjectData.php
+++ b/webseite/classes/SubjectData.php
@@ -64,7 +64,7 @@ class SubjectData
                 continue;
             }
 
-            $result[] = $subjectData;
+            $result[$subjectData->id] = $subjectData;
         }
 
         return $result;
diff --git a/webseite/classes/TopicData.php b/webseite/classes/TopicData.php
index ea09195..6954a24 100644
--- a/webseite/classes/TopicData.php
+++ b/webseite/classes/TopicData.php
@@ -63,7 +63,7 @@ class TopicData
                 continue;
             }
 
-            $result[] = $topicData;
+            $result[$topicData->id] = $topicData;
         }
 
         return $result;
diff --git a/webseite/subject.php b/webseite/subject.php
index 641fa22..c52c7fe 100644
--- a/webseite/subject.php
+++ b/webseite/subject.php
@@ -621,10 +621,15 @@ $topics = $subjectData->topics;
                         <h4>Verwandte Themen:</h4>
                         <ul>
                             <?php
-                            foreach ($topicData->relatedTopics as $relatedTopic) {
+                            foreach ($topicData->relatedTopics as $relatedTopicName) {
+                                $relatedTopic = $subjectData->topics[$relatedTopicName];
+                                if(!isset($relatedTopicName)) {
+                                    continue;
+                                }
+
                                 ?>
 
-                                <li><?php echo($relatedTopic); ?></li>
+                                <li><?php echo($relatedTopic->displayName); ?></li>
 
                                 <?php
                             }
diff --git a/webseite/topic.php b/webseite/topic.php
index 35cdcc8..7c3c5bf 100644
--- a/webseite/topic.php
+++ b/webseite/topic.php
@@ -373,11 +373,16 @@ if(!isset($topicData)) {
         <h3>Verwandte Themen</h3>
         <div style="display: flex; flex-wrap: wrap; gap: 0.5rem;">
             <?php
-            foreach ($topicData->relatedTopics as $relatedTopic) {
+            foreach ($topicData->relatedTopics as $relatedTopicName) {
+                $relatedTopic = $subjectData->topics[$relatedTopicName];
+                if(!isset($relatedTopic)) {
+                    continue;
+                }
+
                 ?>
 
-                <a href='<?php echo("topic.php?subject=$subjectData->id&topic=$relatedTopic") ?>'>
-                    <span class="topic-tag"><?php echo($relatedTopic); ?></span>
+                <a href='<?php echo("topic.php?subject=$subjectData->id&topic=$relatedTopic->id") ?>'>
+                    <span class="topic-tag"><?php echo($relatedTopic->displayName); ?></span>
                 </a>
 
                 <?php