diff --git a/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/AppSettingsSection.cs b/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/AppSettingsSection.cs
index fa1377743f789f..d34b2757a1ab9d 100644
--- a/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/AppSettingsSection.cs
+++ b/src/libraries/System.Configuration.ConfigurationManager/src/System/Configuration/AppSettingsSection.cs
@@ -127,7 +127,7 @@ protected internal override void DeserializeElement(XmlReader reader, bool seria
                 }
             }
 
-            ConfigXmlReader internalReader = new ConfigXmlReader(rawXml, sourceFileFullPath, lineOffset);
+            using ConfigXmlReader internalReader = new ConfigXmlReader(rawXml, sourceFileFullPath, lineOffset);
             internalReader.Read();
 
             if (internalReader.MoveToNextAttribute())