diff --git a/.gitignore b/.gitignore
index 20e54cf..5c986d1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
+.cache
 vendor
 cmd/protoc-gen-go/protoc-gen-go
diff --git a/.travis.yml b/.travis.yml
index bfff242..0aec6a3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,4 +2,4 @@
   - ./test.bash
 cache:
   directories:
-  - /tmp/golang-protobuf-test
+  - .cache
diff --git a/test.bash b/test.bash
index a755976..d6b8440 100755
--- a/test.bash
+++ b/test.bash
@@ -10,7 +10,7 @@
 # The test directory contains the Go and protobuf toolchains used for testing.
 # The bin directory contains symlinks to each tool by version.
 # It is safe to delete this directory and run the test script from scratch.
-TEST_DIR=/tmp/golang-protobuf-test
+TEST_DIR=$REPO_ROOT/.cache
 mkdir -p $TEST_DIR/bin
 function register_binary() {
 	rm -f $TEST_DIR/bin/$1 # best-effort delete
@@ -110,7 +110,7 @@
 
 # Check for stale or unformatted source files.
 check go run ./internal/cmd/generate-types
-check gofmt -d .
+check gofmt -d $(cd $REPO_ROOT && git ls-files '*.go')
 
 # Check for changed or untracked files.
 check git diff --no-prefix HEAD