diff --git a/rust/Cargo.toml b/rust/Cargo.toml
index 7bc21bc..deaa12c 100644
--- a/rust/Cargo.toml
+++ b/rust/Cargo.toml
@@ -1,3 +1,7 @@
+# Declare our own workspace so Cargo doesn't auto-include this crate in a
+# downstream workspace when Lake materializes the package under `.lake/`.
+[workspace]
+
 [package]
 name = "blake3-rs"
 version = "0.1.0"