diff --git a/plugins/thumbnails/thumbnails.php b/plugins/thumbnails/thumbnails.php
index 98f9af6..aaa6d53 100755
--- a/plugins/thumbnails/thumbnails.php
+++ b/plugins/thumbnails/thumbnails.php
@@ -155,25 +155,21 @@ class thumbnailGenerator extends BaseProcessor
             $pdfFile = $pdfDir .DIRECTORY_SEPARATOR. $this->document->iId.'.pdf';
 	    }
 		
-		$pdfFile = str_replace('/', '\\', $pdfFile);
-		
         $thumbnaildir = $default->internalVarDirectory.DIRECTORY_SEPARATOR.'thumbnails';
-		if (WINDOWS_OS) {
+
+		if (stristr(PHP_OS,'WIN')) {
 			$thumbnaildir = str_replace('/', '\\', $thumbnaildir);
+			 $pdfFile = str_replace('/', '\\', $pdfFile);
 		}
 
 		if (!preg_match('/' . str_replace('/', '\/', str_replace('\\', '\\\\', KT_DIR)) . '/', $thumbnaildir))
 		{
-			if (WINDOWS_OS) {
+			if (stristr(PHP_OS,'WIN')) {
 				$thumbnaildir = KT_DIR . '\\' . trim($thumbnaildir, '\\');
 			}
-			else {
-				$thumbnaildir = KT_DIR . '/' . trim($thumbnaildir, '/');
-			}
 		}
 		
         $thumbnailfile = $thumbnaildir.DIRECTORY_SEPARATOR.$this->document->iId.'.jpg';
-		
         //if thumbail dir does not exist, generate one and add an index file to block access
         if (!file_exists($thumbnaildir)) {
         	 mkdir($thumbnaildir, 0755);
@@ -186,7 +182,6 @@ class thumbnailGenerator extends BaseProcessor
             $default->log->debug('Thumbnail Generator Plugin: PDF file does not exist, cannot generate a thumbnail');
             return false;
         }
-        
 		// if a previous version of the thumbnail exists - delete it
 		if (file_exists($thumbnailfile)) {
 			@unlink($thumbnailfile);
@@ -196,13 +191,12 @@ class thumbnailGenerator extends BaseProcessor
             $pathConvert = (!empty($default->convertPath)) ? $default->convertPath : 'convert';
             // windows path may contain spaces
 
-            if (WINDOWS_OS) {
+            if (stristr(PHP_OS,'WIN')) {
 				$cmd = "\"{$pathConvert}\" -size 200x200 \"{$pdfFile}[0]\" -resize 200x200 \"$thumbnailfile\"";
             }
 			else {
 				$cmd = "{$pathConvert} -size 200x200 {$pdfFile}[0] -resize 200x200 $thumbnailfile";
 			}
-			
         	$result = KTUtil::pexec($cmd);
         	return true;
         //}else{
@@ -239,18 +233,15 @@ class ThumbnailViewlet extends KTDocumentViewlet {
 		$varDir = $default->internalVarDirectory;
 		$thumbnailfile = $varDir . '/thumbnails/'.$documentId.'.jpg';
 		
-		if (WINDOWS_OS) {
+		if (stristr(PHP_OS,'WIN')) {
 			$varDir = str_replace('/', '\\', $varDir);
 		}
 		
 		if (!preg_match('/' . str_replace('/', '\/', str_replace('\\', '\\\\', KT_DIR)) . '/', $thumbnaildir))
 		{
-			if (WINDOWS_OS) {
+			if (stristr(PHP_OS,'WIN')) {
 				$varDir = KT_DIR . '\\' . trim($varDir, '\\');
 			}
-			else {
-				$varDir = KT_DIR . '/' . trim($varDir, '/');
-			}
 		}
 		
 		$thumbnailCheck = $varDir . '/thumbnails/'.$documentId.'.jpg';
@@ -294,4 +285,4 @@ class ThumbnailViewlet extends KTDocumentViewlet {
     }
 }
 
-?>
\ No newline at end of file
+?>