diff --git a/src/doc/rustc-dev-guide/ci/linkcheck.sh b/src/doc/rustc-dev-guide/ci/linkcheck.sh
index db6b35a5b7f2..6979e98678bd 100755
--- a/src/doc/rustc-dev-guide/ci/linkcheck.sh
+++ b/src/doc/rustc-dev-guide/ci/linkcheck.sh
@@ -9,7 +9,7 @@ if [ "$TRAVIS_EVENT_TYPE" = "cron" ] ; then # running in cron job
 
   echo "Doing full link check."
 elif [ "$CI" = "true" ] ; then # running in PR CI build
-  if [ -n "$TRAVIS_COMMIT_RANGE" ]; then
+  if [ -z "$TRAVIS_COMMIT_RANGE" ]; then
     echo "error: unexpected state: COMMIT_RANGE must be non-empty in CI"
     exit 1
   fi