diff --git a/.gitignore b/.gitignore
index 7121c83..7e69498 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 _site/
 preserves.pdf
+scratch/
diff --git a/implementations/rust/.gitignore b/implementations/rust/.gitignore
new file mode 100644
index 0000000..03314f7
--- /dev/null
+++ b/implementations/rust/.gitignore
@@ -0,0 +1 @@
+Cargo.lock