diff --git a/ci.sh b/ci.sh
index dce66c2..85d2a18 100755
--- a/ci.sh
+++ b/ci.sh
@@ -2,6 +2,7 @@
 
 set -ex
 
+CHECK_FILES="setup.py src tests"
 YAPF_VERSION=0.20.1
 
 python -m pip install -U pip setuptools wheel
@@ -13,8 +14,8 @@ pip install dist/*.zip
 pip install -Ur test-requirements.txt
 
 if [ "$CHECK_FORMATTING" = "1" ]; then
-    pip install yapf==${YAPF_VERSION} isort>=5 mypy pyright
-    if ! yapf -rpd setup.py src tests; then
+    pip install yapf==${YAPF_VERSION} "isort>=5" mypy pyright
+    if ! yapf -rpd $CHECK_FILES; then
         cat <<EOF
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@@ -22,7 +23,7 @@ if [ "$CHECK_FORMATTING" = "1" ]; then
 Formatting problems were found (listed above). To fix them, run
 
    pip install yapf==${YAPF_VERSION}
-   yapf -rpi setup.py src tests
+   yapf -rpi $CHECK_FILES
 
 in your local checkout.
 
@@ -32,7 +33,7 @@ EOF
         exit 1
     fi
 
-    if ! isort --check-only --diff . ; then
+    if ! isort --check-only --diff $CHECK_FILES ; then
         cat <<EOF
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
@@ -40,7 +41,7 @@ EOF
 Formatting problems were found (listed above). To fix them, run
 
    pip install isort
-   isort .
+   isort $CHECK_FILES
 
 in your local checkout.