diff --git a/inc/inc.ClassExtensionMgr.php b/inc/inc.ClassExtensionMgr.php
index 5cd4f1f4c..22eda0f75 100644
--- a/inc/inc.ClassExtensionMgr.php
+++ b/inc/inc.ClassExtensionMgr.php
@@ -565,12 +565,16 @@ class SeedDMS_Extension_Mgr {
 		 * location and leave the extracted archive in place. The next time an
 		 * extension is imported the last extracted archive will be removed.
 		 */
-//		if(!rename($newdir, $this->extdir ."/". $extname)) {
-		if(false === exec('mv '.escapeshellarg($newdir).' '.escapeshellarg($this->extdir."/".$extname))) {
+		if(strpos(PHP_OS, 'WIN') === 0)
+			$ret = rename($newdir, $this->extdir ."/". $extname);
+		else
+			$ret = exec('mv '.escapeshellarg($newdir).' '.escapeshellarg($this->extdir."/".$extname));
+		if(false === $ret) {
 			/* If copy didn't succeed, then there is probably nothing to delete,
 			 * but do it anyway, just to be sure not just parts of the extension
 			 * has been copied.
 			 */
+			$this->errmsgs[] = "Cannot move temp. extension directory to final destination";
 			$this->rrmdir($this->extdir ."/". $extname);
 			return false;
 		}