diff --git a/lib/system.js b/lib/system.js
index 2e3453f..786ab68 100644
--- a/lib/system.js
+++ b/lib/system.js
@@ -27,7 +27,22 @@ exports.createProcess = function(cmd) {
 };
 
 exports.getEnvString = function(envName) {
-    return WSH.ExpandEnvironmentStrings('%' + envName + '%');
+    var envName = envName.toUpperCase();
+    var resolvedEnvString = WSH.ExpandEnvironmentStrings('%' + envName + '%');
+
+    // Fixed: [lib/system] A few environment variables cannot be referenced in ScriptControl mode. #79
+    if (resolvedEnvString == "") {
+        resolvedEnvString = (function(s) {
+            switch(s) {
+                case "PROGRAMFILES":
+                    return WSH.ExpandEnvironmentStrings("%HOMEDRIVE%\\Program Files");
+                case "PROGRAMFILES(X86)":
+                    return WSH.ExpandEnvironmentStrings("%HOMEDRIVE%\\Program Files (x86)");
+            }
+        })(envName);
+    }
+
+    return resolvedEnvString;
 };
 
 exports.get32BitFolder = function() {