diff --git a/tests/functional/lib/bash/test_header b/tests/functional/lib/bash/test_header
index 915821c0889..a9a5318fc45 100644
--- a/tests/functional/lib/bash/test_header
+++ b/tests/functional/lib/bash/test_header
@@ -434,7 +434,7 @@ grep_workflow_log_ok() {
     local PATTERN="$2"
     shift 2
     local LOG_FILE="${WORKFLOW_RUN_DIR}/log/scheduler/log"
-    if grep "$@" -s -e "$PATTERN" "$LOG_FILE"; then
+    if grep "$@" -s -e -q "$PATTERN" "$LOG_FILE"; then
         ok "${TEST_NAME}"
         return
     fi
diff --git a/tests/functional/optional-outputs/01-stall-on-incomplete.t b/tests/functional/optional-outputs/01-stall-on-incomplete.t
index 64305e5eb3c..1f576450a1b 100644
--- a/tests/functional/optional-outputs/01-stall-on-incomplete.t
+++ b/tests/functional/optional-outputs/01-stall-on-incomplete.t
@@ -30,7 +30,7 @@ workflow_run_fail "${TEST_NAME_BASE}-run" \
 
 LOG="${WORKFLOW_RUN_DIR}/log/scheduler/log"
 grep_ok "Incomplete tasks" "${LOG}"
-grep_ok "1/foo did not complete the required outputs:\n(.*\n){3}.*y$" "${LOG}" -Pizo
+grep_ok '1/foo did not complete the required outputs:\n(.*\n){3}.*y$' "${LOG}" -Pizo
 grep_ok "Workflow stalled" "${LOG}"
 
 purge
diff --git a/tests/functional/spawn-on-demand/19-submitted-compat.t b/tests/functional/spawn-on-demand/19-submitted-compat.t
index daf26b63f15..ec066a928ba 100644
--- a/tests/functional/spawn-on-demand/19-submitted-compat.t
+++ b/tests/functional/spawn-on-demand/19-submitted-compat.t
@@ -54,7 +54,7 @@ grep_workflow_log_ok \
     '\[1/a/01:running\] => succeeded'
 grep_workflow_log_ok \
     "${TEST_NAME_BASE}-b-incomplete" \
-    "1/b did not complete the required outputs:\n.*\n.*submitted.*\n.*succeeded" \
+    '1/b did not complete the required outputs:\n.*\n.*submitted.*\n.*succeeded' \
     -Pizo
 
 purge