diff --git a/src/ci/scripts/should-skip-this.sh b/src/ci/scripts/should-skip-this.sh
index 469f234e410..fa738fe70c8 100755
--- a/src/ci/scripts/should-skip-this.sh
+++ b/src/ci/scripts/should-skip-this.sh
@@ -26,8 +26,10 @@ elif ! git diff --quiet "$BASE_COMMIT" -- src/tools/clippy src/tools/rustfmt; th
     # There is not an easy blanket search for subtrees. For now, manually list
     # the subtrees.
     echo "Executing the job since clippy or rustfmt subtree was updated"
-elif (git diff --name-only HEAD^ | grep --quiet src/test/rustdoc-gui) || \
-     (git diff --name-only HEAD^ | grep --quiet src/librustdoc); then
+elif ! (git diff --quiet "$BASE_COMMIT" -- \
+         src/test/rustdoc-gui \
+         src/librustdoc \
+         src/tools/rustdoc-gui); then
     # There was a change in either rustdoc or in its GUI tests.
     echo "Executing the job since rustdoc was updated"
 else