diff --git a/src/ncc/Classes/NccExtension/ConstantCompiler.php b/src/ncc/Classes/NccExtension/ConstantCompiler.php
index c485856..14cfdcd 100644
--- a/src/ncc/Classes/NccExtension/ConstantCompiler.php
+++ b/src/ncc/Classes/NccExtension/ConstantCompiler.php
@@ -257,7 +257,7 @@
 
             if(function_exists('getcwd'))
             {
-                $input = str_replace(RuntimeConstants::CWD, getcwd(), $input);
+                $input = str_replace(RuntimeConstants::CWD->value, getcwd(), $input);
             }
             else
             {
@@ -266,7 +266,7 @@
 
             if(function_exists('getmypid'))
             {
-                $input = str_replace(RuntimeConstants::PID, getmypid(), $input);
+                $input = str_replace(RuntimeConstants::PID->value, getmypid(), $input);
             }
             else
             {
@@ -275,7 +275,7 @@
 
             if(function_exists('getmyuid'))
             {
-                $input = str_replace(RuntimeConstants::UID, getmyuid(), $input);
+                $input = str_replace(RuntimeConstants::UID->value, getmyuid(), $input);
             }
             else
             {
@@ -284,7 +284,7 @@
 
             if(function_exists('getmygid'))
             {
-                $input = str_replace(RuntimeConstants::GID, getmygid(), $input);
+                $input = str_replace(RuntimeConstants::GID->value, getmygid(), $input);
             }
             else
             {
@@ -293,7 +293,7 @@
 
             if(function_exists('get_current_user'))
             {
-                $input = str_replace(RuntimeConstants::USER, get_current_user(), $input);
+                $input = str_replace(RuntimeConstants::USER->value, get_current_user(), $input);
             }
             else
             {
diff --git a/src/ncc/Enums/SpecialConstants/RuntimeConstants.php b/src/ncc/Enums/SpecialConstants/RuntimeConstants.php
index e9a9845..96a4ee4 100644
--- a/src/ncc/Enums/SpecialConstants/RuntimeConstants.php
+++ b/src/ncc/Enums/SpecialConstants/RuntimeConstants.php
@@ -22,11 +22,11 @@
 
     namespace ncc\Enums\SpecialConstants;
 
-    final class RuntimeConstants
+    enum RuntimeConstants : string
     {
-        public const CWD = '%CWD%';
-        public const PID = '%PID%';
-        public const UID = '%UID%';
-        public const GID = '%GID%';
-        public const USER = '%USER%';
+        case CWD = '%CWD%';
+        case PID = '%PID%';
+        case UID = '%UID%';
+        case GID = '%GID%';
+        case USER = '%USER%';
     }
\ No newline at end of file
diff --git a/src/ncc/Objects/ProjectConfiguration/ExecutionPolicy/Execute.php b/src/ncc/Objects/ProjectConfiguration/ExecutionPolicy/Execute.php
index 8ff95e2..387afa2 100644
--- a/src/ncc/Objects/ProjectConfiguration/ExecutionPolicy/Execute.php
+++ b/src/ncc/Objects/ProjectConfiguration/ExecutionPolicy/Execute.php
@@ -81,7 +81,7 @@
         public function __construct(string $target, ?string $working_directory=null)
         {
             $this->target = $target;
-            $this->working_directory = $working_directory ?? RuntimeConstants::CWD;
+            $this->working_directory = $working_directory ?? RuntimeConstants::CWD->value;
             $this->options = [];
             $this->environment_variables = [];
             $this->silent = false;
@@ -116,7 +116,7 @@
          */
         public function getWorkingDirectory(): string
         {
-            return $this->working_directory ?? RuntimeConstants::CWD;
+            return $this->working_directory ?? RuntimeConstants::CWD->value;
         }
 
         /**
@@ -127,7 +127,7 @@
          */
         public function setWorkingDirectory(?string $working_directory): void
         {
-            $this->working_directory = $working_directory ?? RuntimeConstants::CWD;
+            $this->working_directory = $working_directory ?? RuntimeConstants::CWD->value;
         }
 
         /**