diff --git a/ci/audit.yml b/ci/audit.yml
index 4de4d5f..eec435a 100644
--- a/ci/audit.yml
+++ b/ci/audit.yml
@@ -4,13 +4,15 @@ image_resource:
   type: registry-image
   source: {repository: rust}
 
-# move cargo's config directory to be ./.cargo-config/ and cache it
+# move rust's config directories to be in the current directory, so they can be cached.
 params:
   CARGO_HOME: "./.cargo-config"
+  RUSTUP_HOME: "./.rustup-config"
 
 caches:
   - path: "./repo/target"
   - path: "./repo/.cargo-config"
+  - path: "./repo/.rustup-config"
 
 
 inputs:
diff --git a/ci/build-linux.yml b/ci/build-linux.yml
index 000bf0e..229083c 100644
--- a/ci/build-linux.yml
+++ b/ci/build-linux.yml
@@ -4,9 +4,10 @@ image_resource:
   type: registry-image
   source: {repository: rust}
 
-# move cargo's config directory to be ./.cargo-config/ and cache it
+# move rust's config directories to be in the current directory, so they can be cached.
 params:
   CARGO_HOME: "./.cargo-config"
+  RUSTUP_HOME: "./.rustup-config"
 
 caches:
   - path: "./repo/target"
diff --git a/ci/check-fmt.yml b/ci/check-fmt.yml
index ca12cf5..3afd882 100644
--- a/ci/check-fmt.yml
+++ b/ci/check-fmt.yml
@@ -4,9 +4,15 @@ image_resource:
   type: registry-image
   source: {repository: rust}
 
-# This should cache rustfmt
+# move rust's config directories to be in the current directory, so they can be cached.
+params:
+  CARGO_HOME: "./.cargo-config"
+  RUSTUP_HOME: "./.rustup-config"
+
 caches:
-- path: "./.rustup/"
+  - path: "./repo/target"
+  - path: "./repo/.cargo-config"
+  - path: "./repo/.rustup-config"
 
 inputs:
 - name: repo
diff --git a/ci/lint.yml b/ci/lint.yml
index acd53c8..ccb3efa 100644
--- a/ci/lint.yml
+++ b/ci/lint.yml
@@ -4,11 +4,15 @@ image_resource:
   type: registry-image
   source: {repository: rust}
 
-# This should cache clippy
+# move rust's config directories to be in the current directory, so they can be cached.
+params:
+  CARGO_HOME: "./.cargo-config"
+  RUSTUP_HOME: "./.rustup-config"
+
 caches:
-- path: "./.rustup/"
-- path: "./.cargo/"
-- path: "./target/"
+  - path: "./repo/target"
+  - path: "./repo/.cargo-config"
+  - path: "./repo/.rustup-config"
 
 inputs:
 - name: repo
diff --git a/ci/test.yml b/ci/test.yml
index f1c00b0..9d6d2b8 100644
--- a/ci/test.yml
+++ b/ci/test.yml
@@ -4,9 +4,10 @@ image_resource:
   type: registry-image
   source: {repository: rust}
 
-# move cargo's config directory to be ./.cargo-config/ and cache it
+# move rust's config directories to be in the current directory, so they can be cached.
 params:
   CARGO_HOME: "./.cargo-config"
+  RUSTUP_HOME: "./.rustup-config"
 
 caches:
   - path: "./repo/target"