diff --git a/update_psa_impl b/update_psa_impl
index d937a77..98ac476 100755
--- a/update_psa_impl
+++ b/update_psa_impl
@@ -28,11 +28,13 @@ collect_current_configuration () {
     #done
 }
 
-update_psa() {
+update_psa() { # calling with a parameter is used for testing
 
-    if ! updates_available; then    # check for false alarm
-        update_psa_false_alarm "update requested, but no WAIT state detected"
-        exit $?
+    if [ $# -eq 0 ]; then
+        if ! updates_available; then    # check for false alarm
+            update_psa_false_alarm "update requested, but no WAIT state detected"
+            exit $EXITCODE
+        fi
     fi
 
     update_psa_activated    # message to ISMAS