diff --git a/tests/utils/shippable/nox.sh b/tests/utils/shippable/nox.sh
index 3aa74af3..b62a4722 100755
--- a/tests/utils/shippable/nox.sh
+++ b/tests/utils/shippable/nox.sh
@@ -60,8 +60,8 @@ if [ -n "${COMPLETE:-}" ]; then
 elif [[ "${COMMIT_MESSAGE}" =~ ci_complete ]]; then
     # disable change detection triggered by having 'ci_complete' in the latest commit message
     export ANTSIBULL_CHANGE_DETECTION=""
-else
-    # enable change detection (default behavior)
+if [ "${IS_PULL_REQUEST:-}" == "true" ]; then
+    # enable change detection for PRs (default behavior)
     export ANTSIBULL_CHANGE_DETECTION="true"
     export ANTSIBULL_BASE_BRANCH="${SYSTEM_PULLREQUEST_TARGETBRANCH}"
     # Create a branch for the current HEAD, which happens to be a merge commit
@@ -70,6 +70,9 @@ else
     git branch "${SYSTEM_PULLREQUEST_TARGETBRANCH}" --track "origin/${SYSTEM_PULLREQUEST_TARGETBRANCH}"
     # Show branches
     git branch -vv
+else
+    # disable change detection for pushes and scheduled runs
+    export ANTSIBULL_CHANGE_DETECTION=""
 fi
 
 if [[ "${COVERAGE:-}" == "--coverage" ]]; then