diff --git a/src/fsfw/action/ActionHelper.cpp b/src/fsfw/action/ActionHelper.cpp
index dcc5993d..b28532df 100644
--- a/src/fsfw/action/ActionHelper.cpp
+++ b/src/fsfw/action/ActionHelper.cpp
@@ -83,7 +83,7 @@ void ActionHelper::prepareExecution(MessageQueueId_t commandedBy, ActionId_t act
   }
   Action* action = actionIter->second;
   result = action->deSerialize(&dataPtr, &size, SerializeIF::Endianness::NETWORK);
-  if ((result != HasReturnvaluesIF::RETURN_OK)){
+  if ((result != returnvalue::OK) or (size != 0)){
     CommandMessage reply;
     ActionMessage::setStepReply(&reply, actionId, 0, HasActionsIF::INVALID_PARAMETERS);
     queueToUse->sendMessage(commandedBy, &reply);
diff --git a/src/fsfw/action/SimpleActionHelper.cpp b/src/fsfw/action/SimpleActionHelper.cpp
index df1f2118..b64c75da 100644
--- a/src/fsfw/action/SimpleActionHelper.cpp
+++ b/src/fsfw/action/SimpleActionHelper.cpp
@@ -57,7 +57,7 @@ void SimpleActionHelper::prepareExecution(MessageQueueId_t commandedBy, ActionId
   }
   Action* action = actionIter->second;
   result = action->deSerialize(&dataPtr, &size, SerializeIF::Endianness::NETWORK);
-  if (result != HasReturnvaluesIF::RETURN_OK){
+  if ((result != returnvalue::OK) or (size != 0)) {
     CommandMessage reply;
     ActionMessage::setStepReply(&reply, actionId, 0, HasActionsIF::INVALID_PARAMETERS);
     queueToUse->sendMessage(commandedBy, &reply);