diff --git a/backup/cc/cc2moodle.php b/backup/cc/cc2moodle.php
index 0728daca872ec..59d5230d4bb03 100644
--- a/backup/cc/cc2moodle.php
+++ b/backup/cc/cc2moodle.php
@@ -381,7 +381,7 @@ protected function create_node_course_blocks_block () {
         if (!empty($format['defaultblocks'])) {
             $blocknames = $format['defaultblocks'];
         } else {
-            if (!empty($CFG->defaultblocks)) {
+            if (isset($CFG->defaultblocks)) {
                 $blocknames = $CFG->defaultblocks;
             } else {
                 $blocknames = 'participants,activity_modules,search_forums,course_list:news_items,calendar_upcoming,recent_activity';
diff --git a/course/format/lib.php b/course/format/lib.php
index 84013efd9611c..ae2b9a1c8d28d 100644
--- a/course/format/lib.php
+++ b/course/format/lib.php
@@ -477,7 +477,7 @@ public function extend_course_navigation($navigation, navigation_node $node) {
      */
     public function get_default_blocks() {
         global $CFG;
-        if (!empty($CFG->defaultblocks)){
+        if (isset($CFG->defaultblocks)) {
             return blocks_parse_default_blocks_list($CFG->defaultblocks);
         }
         $blocknames = array(
diff --git a/lib/blocklib.php b/lib/blocklib.php
index fd7c2c0cd0fc3..315636a308d91 100644
--- a/lib/blocklib.php
+++ b/lib/blocklib.php
@@ -2209,7 +2209,7 @@ function blocks_parse_default_blocks_list($blocksstr) {
 function blocks_get_default_site_course_blocks() {
     global $CFG;
 
-    if (!empty($CFG->defaultblocks_site)) {
+    if (isset($CFG->defaultblocks_site)) {
         return blocks_parse_default_blocks_list($CFG->defaultblocks_site);
     } else {
         return array(
@@ -2227,13 +2227,13 @@ function blocks_get_default_site_course_blocks() {
 function blocks_add_default_course_blocks($course) {
     global $CFG;
 
-    if (!empty($CFG->defaultblocks_override)) {
+    if (isset($CFG->defaultblocks_override)) {
         $blocknames = blocks_parse_default_blocks_list($CFG->defaultblocks_override);
 
     } else if ($course->id == SITEID) {
         $blocknames = blocks_get_default_site_course_blocks();
 
-    } else if (!empty($CFG->{'defaultblocks_' . $course->format})) {
+    } else if (isset($CFG->{'defaultblocks_' . $course->format})) {
         $blocknames = blocks_parse_default_blocks_list($CFG->{'defaultblocks_' . $course->format});
 
     } else {