diff --git a/picture.php b/picture.php
index 38416c0a9..153f6276b 100644
--- a/picture.php
+++ b/picture.php
@@ -971,12 +971,14 @@ SELECT id, name, permalink
   }
 }
 
-$template->assign(
-  array(
-    'PDF_VIEWER_FILESIZE_THRESHOLD' => $conf['pdf_viewer_filesize_threshold']*1024,
-    'PDF_NB_PAGES' => count_pdf_pages($picture['current']['path'])
-  )
-);
+if (str_ends_with(strtolower($picture['current']['file']), "pdf" )) {
+  $template->assign(
+    array(
+      'PDF_VIEWER_FILESIZE_THRESHOLD' => $conf['pdf_viewer_filesize_threshold']*1024,
+      'PDF_NB_PAGES' => count_pdf_pages($picture['current']['path'])
+    )
+  );
+}
 
 // maybe someone wants a special display (call it before page_header so that
 // they can add stylesheets)
@@ -1044,4 +1046,4 @@ else
 //------------------------------------------------------------ log informations
 pwg_log($picture['current']['id'], 'picture');
 include(PHPWG_ROOT_PATH.'include/page_tail.php');
-?>
\ No newline at end of file
+?>