diff --git a/src/EntitySet.php b/src/EntitySet.php
index dd1e64e99..ae264711a 100644
--- a/src/EntitySet.php
+++ b/src/EntitySet.php
@@ -266,6 +266,7 @@ public function get(Transaction $transaction, ?ContextInterface $context = null)
         }
 
         $this->assertValidOrderBy();
+        $this->assertValidFilter();
 
         return $transaction->getResponse()->setResourceCallback($this, function () use ($transaction, $context) {
             $context = $context ?: $this;
@@ -1131,6 +1132,25 @@ protected function assertValidOrderBy(): void
         }
     }
 
+    /**
+     * Assert that the $filter expression is syntactically valid and references only known properties.
+     * This runs BEFORE the streaming response begins so that an invalid filter yields HTTP 400
+     * rather than a malformed mid-stream error fragment.
+     * @return void
+     */
+    protected function assertValidFilter(): void
+    {
+        $filter = $this->getFilter();
+
+        if (!$filter->hasValue()) {
+            return;
+        }
+
+        $parser = $this->getFilterParser();
+        $parser->pushEntitySet($this);
+        $parser->generateTree($filter->getExpression());
+    }
+
     /**
      * Assert that the attached type has searchable properties
      * @return void