diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 98d7ff3..ce1cce0 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,5 +1,24 @@
 <?xml version="1.0" encoding="utf-8"?>
-<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd" bootstrap="./tests/bootstrap.php" colors="true" defaultTimeLimit="5" executionOrder="random" enforceTimeLimit="true" cacheDirectory=".phpunit.cache" requireCoverageMetadata="true" beStrictAboutCoverageMetadata="true">
+<phpunit
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
+    bootstrap="./tests/bootstrap.php"
+    colors="true"
+    defaultTimeLimit="5"
+    executionOrder="random"
+    enforceTimeLimit="true"
+    cacheDirectory=".phpunit.cache"
+    requireCoverageMetadata="true"
+    beStrictAboutCoverageMetadata="true"
+    failOnNotice="true"
+    displayDetailsOnTestsThatTriggerNotices="true"
+    failOnDeprecation="true"
+    displayDetailsOnTestsThatTriggerDeprecations="true"
+    failOnWarning="true"
+    displayDetailsOnTestsThatTriggerWarnings="true"
+    beStrictAboutOutputDuringTests="true"
+    displayDetailsOnTestsThatTriggerErrors="true"
+>
   <php>
     <ini name="assert.exception" value="1"/>
   </php>
diff --git a/src/Merge/ReferenceNormalizer.php b/src/Merge/ReferenceNormalizer.php
index cf8221e..a25f311 100644
--- a/src/Merge/ReferenceNormalizer.php
+++ b/src/Merge/ReferenceNormalizer.php
@@ -149,16 +149,18 @@ public function normalizeInlineReferences(
 
                 /** @var array<string, Response> $allSchemas */
                 $allSchemas = $openApiDefinition->components->responses;
+                $allContents = $allSchemas[$key]->content;
                 foreach ($response->content as $contentKey => $content) {
                     if (! $content->schema instanceof Schema) {
                         continue;
                     }
 
-                    $allSchemas[$key]->content[$contentKey]->schema = $this->normalizeProperties(
+                    $allContents[$contentKey]->schema = $this->normalizeProperties(
                         $content->schema,
                         $refFileCollection,
                     );
                 }
+                $allSchemas[$key]->content = $allContents;
 
                 $openApiDefinition->components->responses = $allSchemas;
             }
diff --git a/tests/Merge/Fixtures/expected/openapi-normalized.json b/tests/Merge/Fixtures/expected/openapi-normalized.json
index 2fcf606..bf97d1d 100644
--- a/tests/Merge/Fixtures/expected/openapi-normalized.json
+++ b/tests/Merge/Fixtures/expected/openapi-normalized.json
@@ -158,7 +158,27 @@
     "components": {
         "responses": {
             "reference-101": {
-                "description": "OK"
+                "description": "OK",
+                "content": {
+                    "text\/json": {
+                        "schema": {
+                            "properties": {
+                                "dummyJSON": {
+                                    "$ref": "#\/components\/schemas\/requestBody"
+                                }
+                            }
+                        }
+                    },
+                    "application\/json": {
+                        "schema": {
+                            "properties": {
+                                "dummyApplicationJSON": {
+                                    "$ref": "#\/components\/schemas\/requestBody"
+                                }
+                            }
+                        }
+                    }
+                }
             }
         }
     }
diff --git a/tests/Merge/Fixtures/openapi-with-reference.json b/tests/Merge/Fixtures/openapi-with-reference.json
index 25f5a95..a5a1f02 100644
--- a/tests/Merge/Fixtures/openapi-with-reference.json
+++ b/tests/Merge/Fixtures/openapi-with-reference.json
@@ -161,7 +161,28 @@
     "components": {
         "responses": {
             "reference-101": {
-                "description": "OK"
+                "description": "OK",
+                "content": {
+                    "text/json": {
+                        "schema": {
+                            "properties": {
+                                "dummyJSON": {
+                                    "$ref": "./requestBody.json#/components/schemas/requestBody"
+                                }
+                            }
+                        }
+                    },
+                    "application/json": {
+                        "schema": {
+                            "properties": {
+
+                                "dummyApplicationJSON": {
+                                    "$ref": "./requestBody.json#/components/schemas/requestBody"
+                                }
+                            }
+                        }
+                    }
+                }
             }
         }
     }