diff --git a/lib/Context/ExclusionContext.php b/lib/Context/ExclusionContext.php
index 63cc97d..7cf45cb 100644
--- a/lib/Context/ExclusionContext.php
+++ b/lib/Context/ExclusionContext.php
@@ -49,6 +49,7 @@ class ExclusionContext {
     }
 
     public function __clone() {
+        // if the context was cloned because its parent was cloned, change the parent to the clone
         if ($this->parent) {
             $t = debug_backtrace(\DEBUG_BACKTRACE_IGNORE_ARGS | \DEBUG_BACKTRACE_PROVIDE_OBJECT, 2)[1];
             if (($t['object'] ?? null) instanceof self && $t['function'] === "__clone") {
diff --git a/lib/Database.php b/lib/Database.php
index 404f451..1173ae6 100644
--- a/lib/Database.php
+++ b/lib/Database.php
@@ -1461,13 +1461,13 @@ class Database {
         }
         if ($context->folder()) {
             // add a common table expression to list the folder and its children so that we select from the entire subtree
-            $q->setCTE("folders(folder)", "SELECT ? union select id from arsse_folders join folders on parent = folder", "int", $context->folder);
+            $q->setCTE("folders(folder)", "SELECT ? union select id from arsse_folders join folders on coalesce(parent,0) = folder", "int", $context->folder);
             // limit subscriptions to the listed folders
             $q->setWhere("coalesce(arsse_subscriptions.folder,0) in (select folder from folders)");
         }
         if ($context->not->folder()) {
             // add a common table expression to list the folder and its children so that we exclude from the entire subtree
-            $q->setCTE("folders_excluded(folder)", "SELECT ? union select id from arsse_folders join folders_excluded on parent = folder", "int", $context->not->folder);
+            $q->setCTE("folders_excluded(folder)", "SELECT ? union select id from arsse_folders join folders_excluded on coalesce(parent,0) = folder", "int", $context->not->folder);
             // excluded any subscriptions in the listed folders
             $q->setWhereNot("coalesce(arsse_subscriptions.folder,0) in (select folder from folders_excluded)");
         }
diff --git a/tests/cases/Database/SeriesArticle.php b/tests/cases/Database/SeriesArticle.php
index 694aec5..31dcf96 100644
--- a/tests/cases/Database/SeriesArticle.php
+++ b/tests/cases/Database/SeriesArticle.php
@@ -424,6 +424,7 @@ trait SeriesArticle {
         return [
             'Blank context' => [new Context, [1,2,3,4,5,6,7,8,19,20]],
             'Folder tree' => [(new Context)->folder(1), [5,6,7,8]],
+            'Entire folder tree' => [(new Context)->folder(0), [1,2,3,4,5,6,7,8,19,20]],
             'Leaf folder' => [(new Context)->folder(6), [7,8]],
             'Root folder only' => [(new Context)->folderShallow(0), [1,2,3,4]],
             'Shallow folder' => [(new Context)->folderShallow(1), [5,6]],
@@ -506,6 +507,7 @@ trait SeriesArticle {
             'Excluding tag ID 5' => [(new Context)->not->tag(5), [1,2,3,4,5,6]],
             'Excluding tag "Technology"' => [(new Context)->not->tagName("Technology"), [1,2,3,4,19,20]],
             'Excluding tag "Politics"' => [(new Context)->not->tagName("Politics"), [1,2,3,4,5,6]],
+            'Excluding entire folder tree' => [(new Context)->not->folder(0), []],
         ];
     }