diff --git a/filter/tex/latex.php b/filter/tex/latex.php
index e09f7e99bfd..9e7f897c673 100644
--- a/filter/tex/latex.php
+++ b/filter/tex/latex.php
@@ -114,11 +114,14 @@
                 $convertformat = 'png';
             }
             $filename = str_replace(".{$convertformat}", '', $filename);
-            $tex = "{$this->temp_dir}/$filename.tex";
+            $tex = "$filename.tex"; // Absolute paths won't work with openin_any = p setting.
             $dvi = "{$this->temp_dir}/$filename.dvi";
             $ps  = "{$this->temp_dir}/$filename.ps";
             $img = "{$this->temp_dir}/$filename.{$convertformat}";
 
+            // Change directory to temp dir so that we can work with relative paths.
+            chdir($this->temp_dir);
+
             // turn the latex doc into a .tex file in the temp area
             $fh = fopen( $tex, 'w' );
             fputs( $fh, $doc );
@@ -126,7 +129,7 @@
 
             // run latex on document
             $command = "$pathlatex --interaction=nonstopmode --halt-on-error $tex";
-            chdir( $this->temp_dir );
+
             if ($this->execute($command, $log)) { // It allways False on Windows
 //                return false;
             }
diff --git a/filter/tex/texdebug.php b/filter/tex/texdebug.php
index dadbe186183..36808f1b928 100644
--- a/filter/tex/texdebug.php
+++ b/filter/tex/texdebug.php
@@ -238,12 +238,15 @@
         $output .= "<p>base filename for expression is '$md5'</p>\n";
 
         // temporary paths
-        $tex = "$latex->temp_dir/$md5.tex";
+        $tex = "$md5.tex"; // Absolute paths won't work with openin_any = p setting.
         $dvi = "$latex->temp_dir/$md5.dvi";
         $ps = "$latex->temp_dir/$md5.ps";
         $convertformat = get_config('filter_tex', 'convertformat');
         $img = "$latex->temp_dir/$md5.{$convertformat}";
 
+        // Change directory to temp dir so that we can work with relative paths.
+        chdir($latex->temp_dir);
+
         // put the expression as a file into the temp area
         $expression = html_entity_decode($expression);
         $output .= "<p>Processing TeX expression:</p><pre>$expression</pre>\n";
@@ -252,9 +255,6 @@
         fputs($fh, $doc);
         fclose($fh);
 
-        // cd to temp dir
-        chdir($latex->temp_dir);
-
         // step 1: latex command
         $pathlatex = escapeshellarg($pathlatex);
         $cmd = "$pathlatex --interaction=nonstopmode --halt-on-error $tex";