diff --git a/src/Engine/Mod/SimpleEquationMod.php b/src/Engine/Mod/SimpleEquationMod.php
index 176186f2..8d866618 100644
--- a/src/Engine/Mod/SimpleEquationMod.php
+++ b/src/Engine/Mod/SimpleEquationMod.php
@@ -18,9 +18,12 @@ public static function getType(): string
 
     public function __invoke(Engine $engine, array $options): void
     {
+        $operator = SqlEquationOperator::match($options['operator'])
+            ?? throw new \InvalidArgumentException('Invalid equation operator provided');
+
         $filter = SimpleEquationElement::define(
             equationLeft: $options['operand1'],
-            equationOperator: $options['operator'],
+            equationOperator: $operator,
             equationRight: $options['operand2'],
         );
 
@@ -56,4 +59,4 @@ public function configureOptions(OptionsResolver $resolver): void
                 ?? throw new \InvalidArgumentException('Invalid equation operator provided')
         );
     }
-}
\ No newline at end of file
+}
diff --git a/src/Engine/Projector/InteractiveProjector.php b/src/Engine/Projector/InteractiveProjector.php
index 662ff34f..29edf78b 100644
--- a/src/Engine/Projector/InteractiveProjector.php
+++ b/src/Engine/Projector/InteractiveProjector.php
@@ -163,13 +163,11 @@ private function hydrateForm(FormInterface $form, ListSpecification $list): void
             }
             catch (OutOfBoundsException $exception)
             {
-                $filterSourceId = $filterDefinition->getDataSource()->getFilterIdentifier();
-
                 throw new FlareException(
                     message: 'Filter form does not contain field: ' . $filterName,
                     previous: $exception,
                     method: __METHOD__,
-                    source: $filterSourceId ? \sprintf('tl_flare_filter.id=%s', $filterSourceId) : 'filter inlined'
+                    source: $filterDefinition->getDataSource()?->getFilterIdentifier() ?? 'filter inlined'
                 );
             }
 
diff --git a/src/FilterElement/SimpleEquationElement.php b/src/FilterElement/SimpleEquationElement.php
index 2dd16704..76e71aec 100644
--- a/src/FilterElement/SimpleEquationElement.php
+++ b/src/FilterElement/SimpleEquationElement.php
@@ -44,7 +44,11 @@ public function __invoke(FilterInvocation $inv, FilterQueryBuilder $qb): void
             SqlEquationOperator::LESS_THAN_EQUALS => $qb->expr()->lte($operand, ':eq_right'),
             SqlEquationOperator::LIKE => $qb->expr()->like($operand, ':eq_right'),
             SqlEquationOperator::NOT_LIKE => $qb->expr()->notLike($operand, ':eq_right'),
+            SqlEquationOperator::IN => $qb->expr()->in($operand, ':eq_right'),
+            SqlEquationOperator::NOT_IN => $qb->expr()->notIn($operand, ':eq_right'),
             SqlEquationOperator::IS_NULL => $qb->expr()->isNull($operand),
+            // the default arm below is a runtime safety net for operators added to the enum later
+            // @phpstan-ignore match.alwaysTrue
             SqlEquationOperator::IS_NOT_NULL => $qb->expr()->isNotNull($operand),
             default => null,
         };
@@ -111,4 +115,4 @@ public static function define(
 
         return $definition;
     }
-}
\ No newline at end of file
+}
diff --git a/src/Model/FilterModel.php b/src/Model/FilterModel.php
index 38b59ecd..1336431c 100644
--- a/src/Model/FilterModel.php
+++ b/src/Model/FilterModel.php
@@ -24,7 +24,7 @@ class FilterModel extends Model implements FilterDataSourceInterface, PtableInfe
 
     public function getFilterIdentifier(): string
     {
-        return (string) $this->id;
+        return \sprintf('%s.id=%s', static::$strTable, $this->id);
     }
 
     public function getFilterType(): string
@@ -116,4 +116,4 @@ public function __get($strKey)
             default => parent::__get($strKey),
         };
     }
-}
\ No newline at end of file
+}
diff --git a/src/Query/Executor/FilterExecutor.php b/src/Query/Executor/FilterExecutor.php
index d3eaa197..0fa014bb 100644
--- a/src/Query/Executor/FilterExecutor.php
+++ b/src/Query/Executor/FilterExecutor.php
@@ -177,7 +177,7 @@ private function createCallbackException(
         return new FilterException(
             \sprintf('[FLARE] Query denied: %s / Callback: %s', $e->getMessage(), $errorMethod),
             code: $e->getCode(), previous: $e, method: $errorMethod,
-            source: \sprintf('tl_flare_filter.id=%s', $filter->getDataSource()->getFilterIdentifier() ?: '0'),
+            source: $filter->getDataSource()?->getFilterIdentifier() ?? 'filter inlined',
         );
     }
-}
\ No newline at end of file
+}