diff --git a/blog/lib.php b/blog/lib.php
index 9190e465881..72ce6ce7ca0 100644
--- a/blog/lib.php
+++ b/blog/lib.php
@@ -181,9 +181,11 @@ function blog_sync_external_entries($externalblog) {
             $filtertags = array_map('trim', $filtertags);
             $filtertags = array_map('strtolower', $filtertags);
 
-            foreach ($categories as $category) {
-                if (in_array(trim(strtolower($category->term)), $filtertags)) {
-                    $containsfiltertag = true;
+            if (!empty($categories)) {
+                foreach ($categories as $category) {
+                    if (in_array(trim(strtolower($category->term)), $filtertags)) {
+                        $containsfiltertag = true;
+                    }
                 }
             }