diff --git a/src/fsfw/pus/Service11TelecommandScheduling.h b/src/fsfw/pus/Service11TelecommandScheduling.h
index f8b17c63..5e446b07 100644
--- a/src/fsfw/pus/Service11TelecommandScheduling.h
+++ b/src/fsfw/pus/Service11TelecommandScheduling.h
@@ -39,6 +39,11 @@ class Service11TelecommandScheduling final : public PusServiceBase {
 
   static constexpr ReturnValue_t INVALID_TYPE_TIME_WINDOW =
       HasReturnvaluesIF::makeReturnCode(CLASS_ID, 1);
+  static constexpr ReturnValue_t TIMESHIFTING_NOT_POSSIBLE =
+      HasReturnvaluesIF::makeReturnCode(CLASS_ID, 2);
+  static constexpr ReturnValue_t INVALID_RELATIVE_TIME =
+      HasReturnvaluesIF::makeReturnCode(CLASS_ID, 3);
+
   // The types of PUS-11 subservices
   enum Subservice : uint8_t {
     ENABLE_SCHEDULING = 1,
diff --git a/src/fsfw/pus/Service11TelecommandScheduling.tpp b/src/fsfw/pus/Service11TelecommandScheduling.tpp
index cc830f12..31957652 100644
--- a/src/fsfw/pus/Service11TelecommandScheduling.tpp
+++ b/src/fsfw/pus/Service11TelecommandScheduling.tpp
@@ -345,7 +345,7 @@ inline ReturnValue_t Service11TelecommandScheduling<MAX_NUM_TCS>::doTimeshiftAct
         "Service11TelecommandScheduling::doTimeshiftActivity: Either 0 or more than 1 TCs found. "
         "No explicit timeshifting possible\n");
 #endif
-    return RETURN_FAILED;
+    return TIMESHIFTING_NOT_POSSIBLE;
   }
 
   // temporarily hold the item
@@ -380,7 +380,7 @@ inline ReturnValue_t Service11TelecommandScheduling<MAX_NUM_TCS>::doFilterTimesh
     return result;
   }
   if (relativeTime == 0) {
-    return RETURN_FAILED;
+    return INVALID_RELATIVE_TIME;
   }
 
   // Do time window