diff --git a/plugins/thumbnails/thumbnails.php b/plugins/thumbnails/thumbnails.php
index 2065db6..f9cef7c 100755
--- a/plugins/thumbnails/thumbnails.php
+++ b/plugins/thumbnails/thumbnails.php
@@ -152,17 +152,17 @@ class thumbnailGenerator extends BaseProcessor
             $pdfFile = $pdfDir . DIRECTORY_SEPARATOR . $this->document->getStoragePath();
 	    }else{
     	    $pdfDir = $default->pdfDirectory;
-            $pdfFile = $pdfDir .'/'. $this->document->iId.'.pdf';
+            $pdfFile = $pdfDir .DIRECTORY_SEPARATOR. $this->document->iId.'.pdf';
 	    }
 
-        $thumbnaildir = $default->internalVarDirectory.'/thumbnails';
-        $thumbnailfile = $thumbnaildir.'/'.$this->document->iId.'.jpg';
+        $thumbnaildir = $default->internalVarDirectory.DIRECTORY_SEPARATOR.'thumbnails';
+        $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);
-        	 touch($thumbnaildir.'/index.html');
-        	 file_put_contents($thumbnaildir.'/index.html', 'You do not have permission to access this directory.');
+        	 touch($thumbnaildir.DIRECTORY_SEPARATOR.'index.html');
+        	 file_put_contents($thumbnaildir.DIRECTORY_SEPARATOR.'index.html', 'You do not have permission to access this directory.');
         }
 
         // if there is no pdf that exists - hop out
@@ -180,9 +180,13 @@ class thumbnailGenerator extends BaseProcessor
             $pathConvert = (!empty($default->convertPath)) ? $default->convertPath : 'convert';
             // windows path may contain spaces
             if (WINDOWS_OS) {
-                $pathConvert = '"' . $pathConvert . '"';
+				$cmd = "\"{$pathConvert}\" -size 200x200 \"{$pdfFile}[0]\" -resize 200x200 \"$thumbnailfile\"";
             }
-        	$result = KTUtil::pexec("{$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{
         	//$default->log->debug('Thumbnail Generator Plugin: Imagemagick not installed, cannot generate a thumbnail');
@@ -216,7 +220,7 @@ class ThumbnailViewlet extends KTDocumentViewlet {
         // Check for the thumbnail
         global $default;
 		$varDir = $default->internalVarDirectory;
-		$thumbnailfile = $varDir . '/thumbnails/'.$documentId.'.jpg';
+		$thumbnailfile = $varDir . DIRECTORY_SEPARATOR . 'thumbnails'. DIRECTORY_SEPARATOR .$documentId.'.jpg';
 
 		// if the thumbnail doesn't exist try to create it
 		if (!file_exists($thumbnailfile)){
@@ -251,7 +255,7 @@ class ThumbnailViewlet extends KTDocumentViewlet {
     public function get_width($documentId){
     	global $default;
     	$varDir = $default->internalVarDirectory;
-		$thumbnailfile = $varDir . '/thumbnails/'.$documentId.'.jpg';
+		$thumbnailfile = $varDir . DIRECTORY_SEPARATOR.'thumbnails'.DIRECTORY_SEPARATOR.$documentId.'.jpg';
 		$size = getimagesize($thumbnailfile);
 		return $size[0];
     }