diff --git a/.changeset/happy-weeks-buy.md b/.changeset/happy-weeks-buy.md
new file mode 100644
index 0000000000..61d9f4eb21
--- /dev/null
+++ b/.changeset/happy-weeks-buy.md
@@ -0,0 +1,5 @@
+---
+"@apollo/client": patch
+---
+
+Ensure `MaybeMasked` does not try and unwrap types that contain index signatures.