diff --git a/lib/AbstractException.php b/lib/AbstractException.php
index 5c7ec40d..0806a135 100644
--- a/lib/AbstractException.php
+++ b/lib/AbstractException.php
@@ -10,6 +10,7 @@ abstract class AbstractException extends \Exception {
     const CODES = [        
         "Exception.uncoded"                           => -1,
         "Exception.unknown"                           => 10000,
+        "Exception.constantUnknown"                   => 10001,
         "ExceptionType.strictFailure"                 => 10011,
         "ExceptionType.typeUnknown"                   => 10012,
         "Lang/Exception.defaultFileMissing"           => 10101,
@@ -41,7 +42,6 @@ abstract class AbstractException extends \Exception {
         "Db/Exception.savepointInvalid"               => 10226,
         "Db/Exception.savepointStale"                 => 10227,
         "Db/Exception.resultReused"                   => 10228,
-        "Db/Exception.constantUnknown"                => 10229,
         "Db/ExceptionInput.missing"                   => 10231,
         "Db/ExceptionInput.whitespace"                => 10232,
         "Db/ExceptionInput.tooLong"                   => 10233,
diff --git a/lib/Database.php b/lib/Database.php
index d67f386c..00cd3ca0 100644
--- a/lib/Database.php
+++ b/lib/Database.php
@@ -1019,7 +1019,7 @@ class Database {
                     // id, subscription, feed, modified_date, marked_date, unread, starred, edition
                     break;
                 default:
-                    throw new Db\Exception("constantUnknown", $fields);
+                    throw new Exception("constantUnknown", $fields);
             }
             $q = $this->articleQuery($user, $context, $columns);
             $q->setJoin("left join arsse_enclosures on arsse_enclosures.article is arsse_articles.id");
diff --git a/locale/en.php b/locale/en.php
index f2f21486..e2848473 100644
--- a/locale/en.php
+++ b/locale/en.php
@@ -85,6 +85,8 @@ return [
     'Exception.JKingWeb/Arsse/Exception.uncoded'                           => 'The specified exception symbol {0} has no code specified in AbstractException.php',
     // this should not usually be encountered
     'Exception.JKingWeb/Arsse/Exception.unknown'                           => 'An unknown error has occurred',
+    // indicates programming error
+    'Exception.JKingWeb/Arsse/Exception.constantUnknown'                   => 'Supplied constant value ({0}) is unknown or invalid in the context in which it was used',
     'Exception.JKingWeb/Arsse/ExceptionType.strictFailure'                 => 'Supplied value could not be normalized to {0, select,
         1 {null}
         2 {boolean}
@@ -142,7 +144,6 @@ return [
     'Exception.JKingWeb/Arsse/Db/Exception.savepointInvalid'               => 'Tried to {action} invalid savepoint {index}',
     'Exception.JKingWeb/Arsse/Db/Exception.savepointStale'                 => 'Tried to {action} stale savepoint {index}',
     'Exception.JKingWeb/Arsse/Db/Exception.resultReused'                   => 'Result set already iterated',
-    'Exception.JKingWeb/Arsse/Db/Exception.constantUnknown'                => 'Supplied constant value ({0}) is unknown or invalid in the context in which it was used',
     'Exception.JKingWeb/Arsse/Db/ExceptionInput.missing'                   => 'Required field "{field}" missing while performing action "{action}"',
     'Exception.JKingWeb/Arsse/Db/ExceptionInput.whitespace'                => 'Field "{field}" of action "{action}" may not contain only whitespace',
     'Exception.JKingWeb/Arsse/Db/ExceptionInput.tooLong'                   => 'Field "{field}" of action "{action}" has a maximum length of {max}',
diff --git a/tests/lib/Database/SeriesArticle.php b/tests/lib/Database/SeriesArticle.php
index afab6110..9fcbbbf8 100644
--- a/tests/lib/Database/SeriesArticle.php
+++ b/tests/lib/Database/SeriesArticle.php
@@ -474,7 +474,7 @@ trait SeriesArticle {
             $this->assertEquals($columns, $test, "Fields do not match expectation for verbosity $constant");
         }
         // check that an unknown fieldset produces an exception
-        $this->assertException("constantUnknown", "Db", "Exception");
+        $this->assertException("constantUnknown");
         Arsse::$db->articleList($this->user, (new Context)->article(101), \PHP_INT_MAX);
     }