diff --git a/.changeset/curvy-cups-fly.md b/.changeset/curvy-cups-fly.md
new file mode 100644
index 00000000000..5e934c90817
--- /dev/null
+++ b/.changeset/curvy-cups-fly.md
@@ -0,0 +1,5 @@
+---
+"@smithy/smithy-client": minor
+---
+
+fix(smithy-client): remove support for instanceof operator