diff --git a/UPGRADING.md b/UPGRADING.md
index 01f1a67ddda..57416dc5aa0 100644
--- a/UPGRADING.md
+++ b/UPGRADING.md
@@ -9,6 +9,8 @@
 
 - [BC] The `TDependentListKey` type was removed and replaced with an optional property of the `TIntRange` type.
 
+- [BC] Configuration: `findUnusedCode`'s default value changed from `false` to `true`.
+
 # Upgrading from Psalm 4 to Psalm 5
 ## Changed
 
diff --git a/config.xsd b/config.xsd
index c36262ad15a..bc9d3aab95f 100644
--- a/config.xsd
+++ b/config.xsd
@@ -41,6 +41,7 @@
         <xs:attribute name="checkForThrowsInGlobalScope" type="xs:boolean" default="false" />
         <xs:attribute name="ensureArrayIntOffsetsExist" type="xs:boolean" default="false" />
         <xs:attribute name="ensureArrayStringOffsetsExist" type="xs:boolean" default="false" />
+        <!-- TODO: Psalm 6 - change default to true -->
         <xs:attribute name="findUnusedCode" type="xs:boolean" default="false" />
         <xs:attribute name="findUnusedVariablesAndParams" type="xs:boolean" default="false" />
         <xs:attribute name="findUnusedPsalmSuppress" type="xs:boolean" default="false" />
diff --git a/src/Psalm/Config.php b/src/Psalm/Config.php
index 096d6d32cce..c10a6124713 100644
--- a/src/Psalm/Config.php
+++ b/src/Psalm/Config.php
@@ -60,7 +60,6 @@
 use function class_exists;
 use function clearstatcache;
 use function count;
-use function defined;
 use function dirname;
 use function explode;
 use function extension_loaded;
@@ -70,7 +69,6 @@
 use function filetype;
 use function flock;
 use function fopen;
-use function fwrite;
 use function get_class;
 use function get_defined_constants;
 use function get_defined_functions;
@@ -124,7 +122,6 @@
 use const PHP_VERSION_ID;
 use const PSALM_VERSION;
 use const SCANDIR_SORT_NONE;
-use const STDERR;
 
 /**
  * @psalm-suppress PropertyNotSetInConstructor
@@ -444,7 +441,7 @@ class Config
     public $forbidden_functions = [];
 
     /**
-     * TODO: Psalm 6: Update default to be true and remove warning.
+     * TODO: Psalm 6: Update default to be true
      *
      * @var bool
      */
@@ -1090,14 +1087,10 @@ private static function fromXmlAndPaths(
             $config->use_igbinary = version_compare($igbinary_version, '2.0.5') >= 0;
         }
 
-
         if (isset($config_xml['findUnusedCode'])) {
             $attribute_text = (string) $config_xml['findUnusedCode'];
             $config->find_unused_code = $attribute_text === 'true' || $attribute_text === '1';
             $config->find_unused_variables = $config->find_unused_code;
-        } elseif (!defined('__IS_TEST_ENV__')) {
-            fwrite(STDERR, 'Warning: "findUnusedCode" will be defaulted to "true" in Psalm 6. You should explicitly'
-                . ' enable or disable this setting.' . PHP_EOL);
         }
 
         if (isset($config_xml['findUnusedVariablesAndParams'])) {