diff --git a/CHANGELOG.md b/CHANGELOG.md
index d4a1224..a1823ad 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,21 @@ All notable changes to WooCommerce Tier and Package Prices will be documented in
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.1.11] - 2025-12-22
+
+### Fixed
+
+- **CRITICAL:** Constant redeclaration warnings/errors for plugin constants affecting versions 1.1.3-1.1.10
+- Potential errors when plugin constants (WC_TPP_VERSION, WC_TPP_PLUGIN_DIR, etc.) already defined
+- Plugin initialization failures caused by constant redeclaration
+
+### Technical Details
+
+- Wrapped all `define()` calls in `defined()` checks for WC_TPP_VERSION, WC_TPP_PLUGIN_DIR, WC_TPP_PLUGIN_URL, WC_TPP_PLUGIN_BASENAME
+- Prevents warnings/errors during WordPress plugin activation/deactivation cycles
+- Completes comprehensive protection against all redeclaration issues
+- All global functions and constants now safely guarded
+
 ## [1.1.10] - 2025-12-22
 
 ### Fixed
diff --git a/composer.json b/composer.json
index a2df238..3207f3a 100644
--- a/composer.json
+++ b/composer.json
@@ -1,7 +1,7 @@
 {
     "name": "magdev/wc-tier-package-prices",
     "description": "WooCommerce plugin for tier pricing and package prices with Twig templates",
-    "version": "1.1.10",
+    "version": "1.1.11",
     "type": "wordpress-plugin",
     "license": "GPL-2.0-or-later",
     "authors": [
diff --git a/releases/wc-tier-and-package-prices-1.1.11.zip b/releases/wc-tier-and-package-prices-1.1.11.zip
new file mode 100644
index 0000000..ca7a36e
Binary files /dev/null and b/releases/wc-tier-and-package-prices-1.1.11.zip differ
diff --git a/releases/wc-tier-and-package-prices-1.1.11.zip.md5 b/releases/wc-tier-and-package-prices-1.1.11.zip.md5
new file mode 100644
index 0000000..9625020
--- /dev/null
+++ b/releases/wc-tier-and-package-prices-1.1.11.zip.md5
@@ -0,0 +1 @@
+4a0c0b07b29d4b7046f9d3ff3f091321  releases/wc-tier-and-package-prices-1.1.11.zip
diff --git a/releases/wc-tier-and-package-prices-1.1.11.zip.sha256 b/releases/wc-tier-and-package-prices-1.1.11.zip.sha256
new file mode 100644
index 0000000..8a17c2c
--- /dev/null
+++ b/releases/wc-tier-and-package-prices-1.1.11.zip.sha256
@@ -0,0 +1 @@
+3da9423d136a2ff254b61577ba1f84d4c0f0d1e57bae361ac29c90327feeeceb  releases/wc-tier-and-package-prices-1.1.11.zip
diff --git a/wc-tier-and-package-prices.php b/wc-tier-and-package-prices.php
index 299eb6b..121cc1e 100644
--- a/wc-tier-and-package-prices.php
+++ b/wc-tier-and-package-prices.php
@@ -4,7 +4,7 @@
  * Plugin Name: WooCommerce Tier and Package Prices
  * Plugin URI: https://src.bundespruefstelle.ch/magdev/wc-tier-package-prices
  * Description: Add tier pricing and package prices to WooCommerce products with configurable quantities at fixed prices
- * Version: 1.1.10
+ * Version: 1.1.11
  * Author: Marco Graetsch
  * Author URI: https://src.bundespruefstelle.ch/magdev
  * Text Domain: wc-tier-package-prices
@@ -22,10 +22,18 @@ if (!defined('ABSPATH')) {
 }
 
 // Define plugin constants
-define('WC_TPP_VERSION', '1.1.10');
-define('WC_TPP_PLUGIN_DIR', plugin_dir_path(__FILE__));
-define('WC_TPP_PLUGIN_URL', plugin_dir_url(__FILE__));
-define('WC_TPP_PLUGIN_BASENAME', plugin_basename(__FILE__));
+if (!defined('WC_TPP_VERSION')) {
+    define('WC_TPP_VERSION', '1.1.11');
+}
+if (!defined('WC_TPP_PLUGIN_DIR')) {
+    define('WC_TPP_PLUGIN_DIR', plugin_dir_path(__FILE__));
+}
+if (!defined('WC_TPP_PLUGIN_URL')) {
+    define('WC_TPP_PLUGIN_URL', plugin_dir_url(__FILE__));
+}
+if (!defined('WC_TPP_PLUGIN_BASENAME')) {
+    define('WC_TPP_PLUGIN_BASENAME', plugin_basename(__FILE__));
+}
 
 // Load Composer autoloader
 require_once WC_TPP_PLUGIN_DIR . 'vendor/autoload.php';