diff --git a/filter/tex/latex.php b/filter/tex/latex.php
index fe0baf99795..6504610c0fb 100644
--- a/filter/tex/latex.php
+++ b/filter/tex/latex.php
@@ -108,14 +108,16 @@
             fclose( $fh );
 
             // run latex on document
-            $command = "{$CFG->filter_tex_pathlatex} --interaction=nonstopmode --halt-on-error $tex";
+            $pathlatex = escapeshellarg(trim($CFG->filter_tex_pathlatex, " '\""));
+            $command = "{$pathlatex} --interaction=nonstopmode --halt-on-error $tex";
             chdir( $this->temp_dir );
             if ($this->execute($command, $log)) { // It allways False on Windows
 //                return false;
             }
 
             // run dvips (.dvi to .ps)
-            $command = "{$CFG->filter_tex_pathdvips} -E $dvi -o $ps";
+            $pathdvips = escapeshellarg(trim($CFG->filter_tex_pathdvips, " '\""));
+            $command = "{$pathdvips} -E $dvi -o $ps";
             if ($this->execute($command, $log )) {
                 return false;
             }
@@ -126,7 +128,8 @@
             } else {
                 $bg_opt = "";
             }
-            $command = "{$CFG->filter_tex_pathconvert} -density $density -trim $bg_opt $ps $img";
+            $pathconvert = escapeshellarg(trim($CFG->filter_tex_pathconvert, " '\""));
+            $command = "{$pathconvert} -density $density -trim $bg_opt $ps $img";
             if ($this->execute($command, $log )) {
                 return false;
             }
diff --git a/filter/tex/lib.php b/filter/tex/lib.php
index c6b5989fb93..46529031c5a 100644
--- a/filter/tex/lib.php
+++ b/filter/tex/lib.php
@@ -116,9 +116,13 @@ function filter_tex_updatedcallback($name) {
         return;
     }
 
-    if (!(is_file($CFG->filter_tex_pathlatex) && is_executable($CFG->filter_tex_pathlatex) &&
-          is_file($CFG->filter_tex_pathdvips) && is_executable($CFG->filter_tex_pathdvips) &&
-          is_file($CFG->filter_tex_pathconvert) && is_executable($CFG->filter_tex_pathconvert))) {
+    $pathlatex = trim($CFG->filter_tex_pathlatex, " '\"");
+    $pathdvips = trim($CFG->filter_tex_pathdvips, " '\"");
+    $pathconvert = trim($CFG->filter_tex_pathconvert, " '\"");
+
+    if (!(is_file($pathlatex) && is_executable($pathlatex) &&
+          is_file($pathdvips) && is_executable($pathdvips) &&
+          is_file($pathconvert) && is_executable($pathconvert))) {
         // LaTeX, dvips or convert are not available, and mimetex can only produce GIFs so...
         set_config('filter_tex_convertformat', 'gif');
     }
diff --git a/filter/tex/settings.php b/filter/tex/settings.php
index c0244e88bb1..ecedc11ba77 100644
--- a/filter/tex/settings.php
+++ b/filter/tex/settings.php
@@ -50,9 +50,9 @@ if ($ADMIN->fulltree) {
     } else if (PHP_OS=='WINNT' or PHP_OS=='WIN32' or PHP_OS=='Windows') {
         // note: you need Ghostscript installed (standard), miktex (standard)
         // and ImageMagick (install at c:\ImageMagick)
-        $default_filter_tex_pathlatex   = "\"c:\\texmf\\miktex\\bin\\latex.exe\" ";
-        $default_filter_tex_pathdvips   = "\"c:\\texmf\\miktex\\bin\\dvips.exe\" ";
-        $default_filter_tex_pathconvert = "\"c:\\imagemagick\\convert.exe\" ";
+        $default_filter_tex_pathlatex   = "c:\\texmf\\miktex\\bin\\latex.exe";
+        $default_filter_tex_pathdvips   = "c:\\texmf\\miktex\\bin\\dvips.exe";
+        $default_filter_tex_pathconvert = "c:\\imagemagick\\convert.exe";
 
     } else {
         $default_filter_tex_pathlatex   = '';
@@ -60,6 +60,16 @@ if ($ADMIN->fulltree) {
         $default_filter_tex_pathconvert = '';
     }
 
+    $pathlatex = $CFG->filter_tex_pathlatex;
+    $pathdvips = $CFG->filter_tex_pathdvips;
+    $pathconvert = $CFG->filter_tex_pathconvert;
+    if (strrpos($pathlatex . $pathdvips . $pathconvert, '"') or
+            strrpos($pathlatex . $pathdvips . $pathconvert, "'")) {
+        set_config('filter_tex_pathlatex', trim($pathlatex, " '\""));
+        set_config('filter_tex_pathdvips', trim($pathdvips, " '\""));
+        set_config('filter_tex_pathconvert', trim($pathconvert, " '\""));
+    }
+
     $items[] = new admin_setting_configexecutable('filter_tex_pathlatex', get_string('pathlatex', 'admin'), '', $default_filter_tex_pathlatex);
     $items[] = new admin_setting_configexecutable('filter_tex_pathdvips', get_string('pathdvips', 'admin'), '', $default_filter_tex_pathdvips);
     $items[] = new admin_setting_configexecutable('filter_tex_pathconvert', get_string('pathconvert', 'admin'), '', $default_filter_tex_pathconvert);
@@ -74,4 +84,4 @@ if ($ADMIN->fulltree) {
         $item->set_updatedcallback('filter_tex_updatedcallback');
         $settings->add($item);
     }
-}
\ No newline at end of file
+}
diff --git a/filter/tex/texdebug.php b/filter/tex/texdebug.php
index 0817d7e65ec..1e49e8ab59c 100644
--- a/filter/tex/texdebug.php
+++ b/filter/tex/texdebug.php
@@ -200,27 +200,33 @@
         // first check if it is likely to work at all
         $output .= "<h3>Checking executables</h3>\n";
         $executables_exist = true;
-        if (is_file($CFG->filter_tex_pathlatex)) {
-            $output .= "latex executable ($CFG->filter_tex_pathlatex) is readable<br />\n";
+        $pathlatex = trim($CFG->filter_tex_pathlatex, " '\"");
+        if (is_file($pathlatex)) {
+            $output .= "latex executable ($pathlatex) is readable<br />\n";
         }
         else {
             $executables_exist = false;
-            $output .= "<b>Error:</b> latex executable ($CFG->filter_tex_pathlatex) is not readable<br />\n";
+            $output .= "<b>Error:</b> latex executable ($pathlatex) is not readable<br />\n";
         }
-        if (is_file($CFG->filter_tex_pathdvips)) {
-            $output .= "dvips executable ($CFG->filter_tex_pathdvips) is readable<br />\n";
+        $pathlatex = escapeshellarg($pathlatex);
+        $pathdvips = trim($CFG->filter_tex_pathdvips, " '\"");
+        if (is_file($pathdvips)) {
+            $output .= "dvips executable ($pathdvips) is readable<br />\n";
         }
         else {
             $executables_exist = false;
-            $output .= "<b>Error:</b> dvips executable ($CFG->filter_tex_pathdvips) is not readable<br />\n";
+            $output .= "<b>Error:</b> dvips executable ($pathdvips) is not readable<br />\n";
         }
-        if (is_file($CFG->filter_tex_pathconvert)) {
-            $output .= "convert executable ($CFG->filter_tex_pathconvert) is readable<br />\n";
+        $pathdvips = escapeshellarg($pathdvips);
+        $pathconvert = trim($CFG->filter_tex_pathconvert, " '\"");
+        if (is_file($pathconvert)) {
+            $output .= "convert executable ($pathconvert) is readable<br />\n";
         }
         else {
             $executables_exist = false;
-            $output .= "<b>Error:</b> convert executable ($CFG->filter_tex_pathconvert) is not readable<br />\n";
+            $output .= "<b>Error:</b> convert executable ($pathconvert) is not readable<br />\n";
         }
+        $pathconvert = escapeshellarg($pathconvert);
 
         // knowing that it might work..
         $md5 = md5($expression);
@@ -244,15 +250,15 @@
         chdir($latex->temp_dir);
 
         // step 1: latex command
-        $cmd = "$CFG->filter_tex_pathlatex --interaction=nonstopmode --halt-on-error $tex";
+        $cmd = "$pathlatex --interaction=nonstopmode --halt-on-error $tex";
         $output .= execute($cmd);
 
         // step 2: dvips command
-        $cmd = "$CFG->filter_tex_pathdvips -E $dvi -o $ps";
+        $cmd = "$pathdvips -E $dvi -o $ps";
         $output .= execute($cmd);
 
         // step 3: convert command
-        $cmd = "$CFG->filter_tex_pathconvert -density 240 -trim $ps $img ";
+        $cmd = "$pathconvert -density 240 -trim $ps $img ";
         $output .= execute($cmd);
 
         if (!$graphic) {