diff --git a/devicehandlers/DeviceHandlerBase.cpp b/devicehandlers/DeviceHandlerBase.cpp
index a371b413..41acf277 100644
--- a/devicehandlers/DeviceHandlerBase.cpp
+++ b/devicehandlers/DeviceHandlerBase.cpp
@@ -116,7 +116,7 @@ ReturnValue_t DeviceHandlerBase::initialize() {
 	AcceptsDeviceResponsesIF *rawReceiver = objectManager->get<
 			AcceptsDeviceResponsesIF>(rawDataReceiverId);
 
-	if (rawReceiver == NULL) {
+	if (rawReceiver == nullptr) {
 		return RETURN_FAILED;
 	}
 
diff --git a/devicehandlers/FixedSlotSequence.cpp b/devicehandlers/FixedSlotSequence.cpp
index 23bb0e78..f11de94b 100644
--- a/devicehandlers/FixedSlotSequence.cpp
+++ b/devicehandlers/FixedSlotSequence.cpp
@@ -1,5 +1,6 @@
 #include <framework/devicehandlers/FixedSlotSequence.h>
 #include <framework/serviceinterface/ServiceInterfaceStream.h>
+#include <cstdlib>
 
 FixedSlotSequence::FixedSlotSequence(uint32_t setLengthMs) :
 		slotLengthMs(setLengthMs) {
@@ -87,7 +88,15 @@ uint32_t FixedSlotSequence::getLengthMs() const {
 }
 
 ReturnValue_t FixedSlotSequence::checkSequence() const {
-	// Iterate through slotList and check successful creation.
+	if(slotList.empty()) {
+	    error << "Fixed Slot Sequence: Slot list is empty!" << std::endl;
+	    // does check sequence have to be const?
+	    // if I want to check a class, I need the ability to set
+	    // internal class states.
+	    //isEmpty = true;
+	    std::exit(0);
+	}
+    // Iterate through slotList and check successful creation.
 	// Checks if timing is ok (must be ascending) and if all handlers were found.
 	auto slotIt = slotList.begin();
 	uint32_t count = 0;
diff --git a/devicehandlers/FixedSlotSequence.h b/devicehandlers/FixedSlotSequence.h
index 813d2fce..cad7ee87 100644
--- a/devicehandlers/FixedSlotSequence.h
+++ b/devicehandlers/FixedSlotSequence.h
@@ -3,6 +3,7 @@
 
 #include <framework/devicehandlers/FixedSequenceSlot.h>
 #include <framework/objectmanager/SystemObject.h>
+#include <framework/returnvalues/HasReturnvaluesIF.h>
 #include <list>
 #include <set>
 
@@ -23,7 +24,6 @@ using SlotListIter = std::multiset<FixedSequenceSlot>::iterator;
 class FixedSlotSequence {
 public:
 
-
 	/**
 	 * @brief	The constructor of the FixedSlotSequence object.
 	 *
@@ -127,6 +127,8 @@ protected:
 	SlotList slotList;
 
 	uint32_t slotLengthMs;
+
+	bool isEmpty = false;
 };
 
 #endif /* FIXEDSLOTSEQUENCE_H_ */
diff --git a/osal/FreeRTOS/FixedTimeslotTask.cpp b/osal/FreeRTOS/FixedTimeslotTask.cpp
index b1c97420..db0247a4 100644
--- a/osal/FreeRTOS/FixedTimeslotTask.cpp
+++ b/osal/FreeRTOS/FixedTimeslotTask.cpp
@@ -112,7 +112,6 @@ void FixedTimeslotTask::taskFunctionality() {
 			vTaskDelayUntil(&xLastWakeTime, interval);
 			//TODO deadline missed check
 		}
-
 	}
 }
 
diff --git a/test/CatchExample.cpp b/test/CatchExample.cpp
index 4db6a5c2..90fd1ed5 100644
--- a/test/CatchExample.cpp
+++ b/test/CatchExample.cpp
@@ -1,5 +1,7 @@
 // Catch Example.
 // Does not work yet. Problems with linker without main and config folder.
+// propably because global object manager and some config files are not supplied
+// but mandatory for full compilation of the framework.
 // Let Catch provide main():
 
 #if defined(UNIT_TEST)