diff --git a/controller.rst b/controller.rst
index 86b5c5f07ca..5b0f940ca2f 100644
--- a/controller.rst
+++ b/controller.rst
@@ -522,7 +522,7 @@ the ``Request`` class::
 
         // retrieves an HTTP request header, with normalized, lowercase keys
         $request->headers->get('host');
-        $request->headers->get('content_type');
+        $request->headers->get('content-type');
     }
 
 The ``Request`` class has several public properties and methods that return any
diff --git a/create_framework/http_foundation.rst b/create_framework/http_foundation.rst
index 79ff1c953a6..a7c4065d842 100644
--- a/create_framework/http_foundation.rst
+++ b/create_framework/http_foundation.rst
@@ -192,7 +192,7 @@ fingertips thanks to a nice and simple API::
 
     // retrieve an HTTP request header, with normalized, lowercase keys
     $request->headers->get('host');
-    $request->headers->get('content_type');
+    $request->headers->get('content-type');
 
     $request->getMethod();    // GET, POST, PUT, DELETE, HEAD
     $request->getLanguages(); // an array of languages the client accepts
diff --git a/introduction/http_fundamentals.rst b/introduction/http_fundamentals.rst
index c3ad78bf3dc..6e7cb1cf183 100644
--- a/introduction/http_fundamentals.rst
+++ b/introduction/http_fundamentals.rst
@@ -231,7 +231,7 @@ have all the request information at your fingertips::
 
     // retrieves an HTTP request header, with normalized, lowercase keys
     $request->headers->get('host');
-    $request->headers->get('content_type');
+    $request->headers->get('content-type');
 
     $request->getMethod();    // e.g. GET, POST, PUT, DELETE or HEAD
     $request->getLanguages(); // an array of languages the client accepts