diff --git a/src/fsfw/container/ArrayList.h b/src/fsfw/container/ArrayList.h
index f5f74cf1..12bcda99 100644
--- a/src/fsfw/container/ArrayList.h
+++ b/src/fsfw/container/ArrayList.h
@@ -5,6 +5,8 @@
 #include "../serialize/SerializeAdapter.h"
 #include "../serialize/SerializeIF.h"
 
+#include "definitions.h"
+
 /**
  * @brief     A List that stores its values in an array.
  * @details
@@ -19,8 +21,6 @@ class ArrayList {
   friend class SerialArrayListAdapter;
 
  public:
-  static const uint8_t INTERFACE_ID = CLASS_ID::ARRAY_LIST;
-  static const ReturnValue_t FULL = MAKE_RETURN_CODE(0x01);
 
   /**
    * This is the allocating constructor.
@@ -187,7 +187,7 @@ class ArrayList {
    */
   ReturnValue_t insert(T entry) {
     if (size >= maxSize_) {
-      return FULL;
+      return containers::LIST_FULL;
     }
     entries[size] = entry;
     ++size;
diff --git a/src/fsfw/container/FixedMap.h b/src/fsfw/container/FixedMap.h
index 6ed6278d..553d3cac 100644
--- a/src/fsfw/container/FixedMap.h
+++ b/src/fsfw/container/FixedMap.h
@@ -4,16 +4,9 @@
 #include <type_traits>
 #include <utility>
 
-#include "../returnvalues/returnvalue.h"
+#include "definitions.h"
 #include "ArrayList.h"
 
-namespace mapdefs {
-static const uint8_t INTERFACE_ID = CLASS_ID::FIXED_MAP;
-static const ReturnValue_t KEY_ALREADY_EXISTS = MAKE_RETURN_CODE(0x01);
-static const ReturnValue_t MAP_FULL = MAKE_RETURN_CODE(0x02);
-static const ReturnValue_t KEY_DOES_NOT_EXIST = MAKE_RETURN_CODE(0x03);
-}  // namespace mapdefs
-
 /**
  * @brief    Map implementation for maps with a pre-defined size.
  * @details
@@ -78,10 +71,10 @@ class FixedMap : public SerializeIF {
 
   ReturnValue_t insert(key_t key, T value, Iterator* storedValue = nullptr) {
     if (exists(key) == returnvalue::OK) {
-      return mapdefs::KEY_ALREADY_EXISTS;
+      return containers::KEY_ALREADY_EXISTS;
     }
     if (_size == theMap.maxSize()) {
-      return mapdefs::MAP_FULL;
+      return containers::MAP_FULL;
     }
     theMap[_size].first = key;
     theMap[_size].second = value;
@@ -95,7 +88,7 @@ class FixedMap : public SerializeIF {
   ReturnValue_t insert(std::pair<key_t, T> pair) { return insert(pair.first, pair.second); }
 
   ReturnValue_t exists(key_t key) const {
-    ReturnValue_t result = mapdefs::KEY_DOES_NOT_EXIST;
+    ReturnValue_t result = containers::KEY_DOES_NOT_EXIST;
     if (findIndex(key) < _size) {
       result = returnvalue::OK;
     }
@@ -105,7 +98,7 @@ class FixedMap : public SerializeIF {
   ReturnValue_t erase(Iterator* iter) {
     uint32_t i;
     if ((i = findIndex((*iter).value->first)) >= _size) {
-      return mapdefs::KEY_DOES_NOT_EXIST;
+      return containers::KEY_DOES_NOT_EXIST;
     }
     theMap[i] = theMap[_size - 1];
     --_size;
@@ -116,7 +109,7 @@ class FixedMap : public SerializeIF {
   ReturnValue_t erase(key_t key) {
     uint32_t i;
     if ((i = findIndex(key)) >= _size) {
-      return mapdefs::KEY_DOES_NOT_EXIST;
+      return containers::KEY_DOES_NOT_EXIST;
     }
     theMap[i] = theMap[_size - 1];
     --_size;
diff --git a/src/fsfw/container/definitions.h b/src/fsfw/container/definitions.h
new file mode 100644
index 00000000..23620176
--- /dev/null
+++ b/src/fsfw/container/definitions.h
@@ -0,0 +1,15 @@
+#ifndef FSFW_CONTAINER_DEFINITIONS_H_
+#define FSFW_CONTAINER_DEFINITIONS_H_
+
+#include "fsfw/retval.h"
+
+using namespace returnvalue;
+namespace containers {
+static const ReturnValue_t KEY_ALREADY_EXISTS = makeCode(CLASS_ID::FIXED_MAP, 0x01);
+static const ReturnValue_t MAP_FULL = makeCode(CLASS_ID::FIXED_MAP, 0x02);
+static const ReturnValue_t KEY_DOES_NOT_EXIST = makeCode(CLASS_ID::FIXED_MAP, 0x03);
+
+static const ReturnValue_t LIST_FULL = makeCode(CLASS_ID::ARRAY_LIST, 0x01);
+}  // namespace containers
+
+#endif /* FSFW_CONTAINER_DEFINITIONS_H_ */