diff --git a/course/format/topics/format.php b/course/format/topics/format.php
index 80f2ae42454..701398bd04f 100644
--- a/course/format/topics/format.php
+++ b/course/format/topics/format.php
@@ -64,7 +64,7 @@
 /// The left column ...
 
     if (blocks_have_content($pageblocks, BLOCK_POS_LEFT) || $editing) {
-        echo '<td style="width: '.$preferred_width_left.'px;" id="left-column">';
+        echo '<td width="'.$preferred_width_left.'" id="left-column">';
         blocks_print_group($PAGE, $pageblocks, BLOCK_POS_LEFT);
         echo '</td>';
     }
@@ -257,7 +257,7 @@
 
     // The right column
     if (blocks_have_content($pageblocks, BLOCK_POS_RIGHT) || $editing) {
-        echo '<td style="width: '.$preferred_width_right.'px;" id="right-column">';
+        echo '<td width="'.$preferred_width_right.'" id="right-column">';
         blocks_print_group($PAGE, $pageblocks, BLOCK_POS_RIGHT);
         echo '</td>';
     }