diff --git a/backends/open62541/tests/dataTypeImport/CMakeLists.txt b/backends/open62541/tests/dataTypeImport/CMakeLists.txt
index d699d06f..15770822 100644
--- a/backends/open62541/tests/dataTypeImport/CMakeLists.txt
+++ b/backends/open62541/tests/dataTypeImport/CMakeLists.txt
@@ -99,7 +99,7 @@ add_test(NAME compareOptionalStruct_Test
     COMMAND compareOptionalStruct "${CMAKE_CURRENT_SOURCE_DIR}/optionalstruct.xml")
 
 ua_generate_nodeset_and_datatypes(
-    NAME "union2"
+    NAME "union"
     FILE_CSV "${CMAKE_CURRENT_SOURCE_DIR}/union.csv"
     FILE_BSD "${CMAKE_CURRENT_SOURCE_DIR}/union.bsd"
     NAMESPACE_MAP "2:http://yourorganisation.org/union/"
@@ -107,6 +107,16 @@ ua_generate_nodeset_and_datatypes(
     INTERNAL
 )
 
+add_executable(compareUnion compareUnion.c ${UA_TYPES_UNION_SOURCES})
+add_dependencies(compareUnion open62541-generator-ns-union)
+target_link_libraries(compareUnion PRIVATE NodesetLoader open62541::open62541 ${CHECK_LIBRARIES} ${PTHREAD_LIB})
+target_include_directories(compareUnion PRIVATE ${CMAKE_BINARY_DIR}/src_generated)
+target_include_directories(compareUnion PRIVATE ${CHECK_INCLUDE_DIR})
+
+add_test(NAME compareUnion_Test
+  WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR} 
+  COMMAND compareUnion "${CMAKE_CURRENT_SOURCE_DIR}/union.xml")
+
 ua_generate_nodeset_and_datatypes(
     NAME "abstractdatatypemember"
     FILE_CSV "${CMAKE_CURRENT_SOURCE_DIR}/abstractdatatypemember.csv"
@@ -126,18 +136,10 @@ add_test(NAME compareAbstractDataTypeMember_Test
     WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR} 
     COMMAND compareAbstractDataTypeMember "${CMAKE_CURRENT_SOURCE_DIR}/abstractdatatypemember.xml")
 
-add_executable(compareUnion union2.c ${UA_TYPES_UNION2_SOURCES})
-add_dependencies(compareUnion open62541-generator-ns-union2)
-target_link_libraries(compareUnion PRIVATE NodesetLoader open62541::open62541 ${CHECK_LIBRARIES} ${PTHREAD_LIB})
-target_include_directories(compareUnion PRIVATE ${CMAKE_BINARY_DIR}/src_generated)
-target_include_directories(compareUnion PRIVATE ${CHECK_INCLUDE_DIR})
 
-add_test(NAME compareUnion_Test
-  WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR} 
-  COMMAND compareUnion "${CMAKE_CURRENT_SOURCE_DIR}/union.xml")
 
 ua_generate_nodeset_and_datatypes(
-    NAME "optionset2"
+    NAME "optionsetgen"
     FILE_CSV "${CMAKE_CURRENT_SOURCE_DIR}/optionset.csv"
     FILE_BSD "${CMAKE_CURRENT_SOURCE_DIR}/optionset.bsd"
     NAMESPACE_MAP "2:http://yourorganisation.org/optionSet/"
@@ -145,8 +147,8 @@ ua_generate_nodeset_and_datatypes(
     INTERNAL
 )
 
-add_executable(compareOptionset optionset.c ${UA_TYPES_OPTIONSET2_SOURCES})
-add_dependencies(compareOptionset open62541-generator-ns-optionset2)
+add_executable(compareOptionset compareOptionset.c ${UA_TYPES_OPTIONSETGEN_SOURCES})
+add_dependencies(compareOptionset open62541-generator-ns-optionsetgen)
 target_link_libraries(compareOptionset PRIVATE NodesetLoader open62541::open62541 ${CHECK_LIBRARIES} ${PTHREAD_LIB})
 target_include_directories(compareOptionset PRIVATE ${CMAKE_BINARY_DIR}/src_generated)
 target_include_directories(compareOptionset PRIVATE ${CHECK_INCLUDE_DIR})
diff --git a/backends/open62541/tests/dataTypeImport/compareAbstractDataTypeMember.c b/backends/open62541/tests/dataTypeImport/compareAbstractDataTypeMember.c
index 7df89b55..8ab9b701 100644
--- a/backends/open62541/tests/dataTypeImport/compareAbstractDataTypeMember.c
+++ b/backends/open62541/tests/dataTypeImport/compareAbstractDataTypeMember.c
@@ -38,22 +38,28 @@ static void teardown(void)
 #endif
 }
 
-START_TEST(compareDI)
+START_TEST(compareAbstractDataTypeMember)
 {
     ck_assert(NodesetLoader_loadFile(server, nodesetPath, NULL));
 
-    UA_ServerConfig* config = UA_Server_getConfig(server);
+    setNamespaceIndexOfGeneratedStruct(
+        server, "http://yourorganisation.org/AbstractDataTypeMember/",
+        UA_TYPES_ABSTRACTDATATYPEMEMBER, UA_TYPES_ABSTRACTDATATYPEMEMBER_COUNT);
+
+    UA_ServerConfig *config = UA_Server_getConfig(server);
     ck_assert(config->customDataTypes);
 
-    ck_assert(config->customDataTypes->typesSize == UA_TYPES_ABSTRACTDATATYPEMEMBER_COUNT);
+    ck_assert(config->customDataTypes->typesSize ==
+              UA_TYPES_ABSTRACTDATATYPEMEMBER_COUNT);
 
     for (const UA_DataType *generatedType = UA_TYPES_ABSTRACTDATATYPEMEMBER;
          generatedType != UA_TYPES_ABSTRACTDATATYPEMEMBER +
                               UA_TYPES_ABSTRACTDATATYPEMEMBER_COUNT;
          generatedType++)
     {
-        const UA_DataType* importedType = NodesetLoader_getCustomDataType(server, &generatedType->typeId);
-        ck_assert(importedType!=NULL);
+        const UA_DataType *importedType =
+            NodesetLoader_getCustomDataType(server, &generatedType->typeId);
+        ck_assert(importedType != NULL);
         typesAreMatching(generatedType, importedType,
                          &UA_TYPES_ABSTRACTDATATYPEMEMBER[0],
                          config->customDataTypes->types);
@@ -61,13 +67,12 @@ START_TEST(compareDI)
 }
 END_TEST
 
-
 static Suite *testSuite_Client(void)
 {
     Suite *s = suite_create("datatype Import");
     TCase *tc_server = tcase_create("server nodeset import");
     tcase_add_unchecked_fixture(tc_server, setup, teardown);
-    tcase_add_test(tc_server, compareDI);
+    tcase_add_test(tc_server, compareAbstractDataTypeMember);
     suite_add_tcase(s, tc_server);
     return s;
 }
diff --git a/backends/open62541/tests/dataTypeImport/optionset.c b/backends/open62541/tests/dataTypeImport/compareOptionset.c
similarity index 83%
rename from backends/open62541/tests/dataTypeImport/optionset.c
rename to backends/open62541/tests/dataTypeImport/compareOptionset.c
index 98a793be..b764671a 100644
--- a/backends/open62541/tests/dataTypeImport/optionset.c
+++ b/backends/open62541/tests/dataTypeImport/compareOptionset.c
@@ -9,7 +9,7 @@
 #include "check.h"
 
 #include "../testHelper.h"
-#include "open62541/types_optionset2_generated.h"
+#include "open62541/types_optionsetgen_generated.h"
 #include <NodesetLoader/backendOpen62541.h>
 #include <NodesetLoader/dataTypes.h>
 
@@ -38,24 +38,28 @@ static void teardown(void)
 #endif
 }
 
-START_TEST(compareUnion)
+START_TEST(compareOptionSet)
 {
     ck_assert(NodesetLoader_loadFile(server, nodesetPath, NULL));
 
+    setNamespaceIndexOfGeneratedStruct(
+        server, "http://yourorganisation.org/optionSet/",
+        UA_TYPES_OPTIONSETGEN, UA_TYPES_OPTIONSETGEN_COUNT);
+
     UA_ServerConfig *config = UA_Server_getConfig(server);
     ck_assert(config->customDataTypes);
 
-    ck_assert(config->customDataTypes->typesSize == UA_TYPES_OPTIONSET2_COUNT);
+    ck_assert(config->customDataTypes->typesSize == UA_TYPES_OPTIONSETGEN_COUNT);
 
-    for (const UA_DataType *generatedType = UA_TYPES_OPTIONSET2;
+    for (const UA_DataType *generatedType = UA_TYPES_OPTIONSETGEN;
          generatedType !=
-         UA_TYPES_OPTIONSET2 + UA_TYPES_OPTIONSET2_COUNT;
+         UA_TYPES_OPTIONSETGEN + UA_TYPES_OPTIONSETGEN_COUNT;
          generatedType++)
     {
         const UA_DataType *importedType =
             NodesetLoader_getCustomDataType(server, &generatedType->typeId);
         ck_assert(importedType != NULL);
-        typesAreMatching(generatedType, importedType, &UA_TYPES_OPTIONSET2[0],
+        typesAreMatching(generatedType, importedType, &UA_TYPES_OPTIONSETGEN[0],
                          config->customDataTypes->types);
     }
 }
@@ -66,7 +70,7 @@ static Suite *testSuite_Client(void)
     Suite *s = suite_create("datatype Import");
     TCase *tc_server = tcase_create("server nodeset import");
     tcase_add_unchecked_fixture(tc_server, setup, teardown);
-    tcase_add_test(tc_server, compareUnion);
+    tcase_add_test(tc_server, compareOptionSet);
     suite_add_tcase(s, tc_server);
     return s;
 }
diff --git a/backends/open62541/tests/dataTypeImport/compareStructExtended.c b/backends/open62541/tests/dataTypeImport/compareStructExtended.c
index 39e5c637..b81a892d 100644
--- a/backends/open62541/tests/dataTypeImport/compareStructExtended.c
+++ b/backends/open62541/tests/dataTypeImport/compareStructExtended.c
@@ -42,6 +42,10 @@ START_TEST(compareDI)
 {
     ck_assert(NodesetLoader_loadFile(server, nodesetPath, NULL));
 
+    setNamespaceIndexOfGeneratedStruct(server,
+                                       "http://yourorganisation.org/struct/",
+                                       UA_TYPES_STRUCTEXTENDED, UA_TYPES_STRUCTEXTENDED_COUNT);
+
     UA_ServerConfig* config = UA_Server_getConfig(server);
     ck_assert(config->customDataTypes);
 
diff --git a/backends/open62541/tests/dataTypeImport/compareStructSpecialized.c b/backends/open62541/tests/dataTypeImport/compareStructSpecialized.c
index ea80988b..c3da3f62 100644
--- a/backends/open62541/tests/dataTypeImport/compareStructSpecialized.c
+++ b/backends/open62541/tests/dataTypeImport/compareStructSpecialized.c
@@ -16,7 +16,7 @@
 
 UA_Server *server;
 char *nodeset1 = NULL;
-char * nodeset2 = NULL;
+char *nodeset2 = NULL;
 
 static void setup(void)
 {
@@ -46,6 +46,14 @@ START_TEST(compareSpecializedStruct)
     ck_assert(NodesetLoader_loadFile(server, nodeset1, NULL));
     ck_assert(NodesetLoader_loadFile(server, nodeset2, NULL));
 
+    setNamespaceIndexOfGeneratedStruct(server,
+                                       "http://yourorganisation.org/struct/",
+                                       UA_TYPES_STRUCT, UA_TYPES_STRUCT_COUNT);
+
+    setNamespaceIndexOfGeneratedStruct(
+        server, "http://yourorganisation.org/specializedStruct/",
+        UA_TYPES_SPECIALIZEDSTRUCT, UA_TYPES_SPECIALIZEDSTRUCT_COUNT);
+
     UA_ServerConfig *config = UA_Server_getConfig(server);
     ck_assert(config->customDataTypes);
 
diff --git a/backends/open62541/tests/dataTypeImport/compareStructTypes.c b/backends/open62541/tests/dataTypeImport/compareStructTypes.c
index 6ef34d1c..f5e05e9a 100644
--- a/backends/open62541/tests/dataTypeImport/compareStructTypes.c
+++ b/backends/open62541/tests/dataTypeImport/compareStructTypes.c
@@ -42,21 +42,28 @@ START_TEST(compareDI)
 {
     ck_assert(NodesetLoader_loadFile(server, nodesetPath, NULL));
 
-    UA_ServerConfig* config = UA_Server_getConfig(server);
+    setNamespaceIndexOfGeneratedStruct(server,
+                                       "http://yourorganisation.org/struct/",
+                                       UA_TYPES_STRUCT, UA_TYPES_STRUCT_COUNT);
+
+    UA_ServerConfig *config = UA_Server_getConfig(server);
     ck_assert(config->customDataTypes);
 
     ck_assert(config->customDataTypes->typesSize == UA_TYPES_STRUCT_COUNT);
 
-    for(const UA_DataType* generatedType = UA_TYPES_STRUCT; generatedType!= UA_TYPES_STRUCT + UA_TYPES_STRUCT_COUNT; generatedType++)
+    for (const UA_DataType *generatedType = UA_TYPES_STRUCT;
+         generatedType != UA_TYPES_STRUCT + UA_TYPES_STRUCT_COUNT;
+         generatedType++)
     {
-        const UA_DataType* importedType = NodesetLoader_getCustomDataType(server, &generatedType->typeId);
-        ck_assert(importedType!=NULL);
-        typesAreMatching(generatedType, importedType, &UA_TYPES_STRUCT[0], config->customDataTypes->types);
+        const UA_DataType *importedType =
+            NodesetLoader_getCustomDataType(server, &generatedType->typeId);
+        ck_assert(importedType != NULL);
+        typesAreMatching(generatedType, importedType, &UA_TYPES_STRUCT[0],
+                         config->customDataTypes->types);
     }
 }
 END_TEST
 
-
 static Suite *testSuite_Client(void)
 {
     Suite *s = suite_create("datatype Import");
diff --git a/backends/open62541/tests/dataTypeImport/union2.c b/backends/open62541/tests/dataTypeImport/compareUnion.c
similarity index 87%
rename from backends/open62541/tests/dataTypeImport/union2.c
rename to backends/open62541/tests/dataTypeImport/compareUnion.c
index f165bf7c..9ce6a649 100644
--- a/backends/open62541/tests/dataTypeImport/union2.c
+++ b/backends/open62541/tests/dataTypeImport/compareUnion.c
@@ -9,7 +9,7 @@
 #include "check.h"
 
 #include "../testHelper.h"
-#include "open62541/types_union2_generated.h"
+#include "open62541/types_union_generated.h"
 #include <NodesetLoader/backendOpen62541.h>
 #include <NodesetLoader/dataTypes.h>
 
@@ -41,19 +41,23 @@ START_TEST(compareUnion)
 {
     ck_assert(NodesetLoader_loadFile(server, nodesetPath, NULL));
 
+    setNamespaceIndexOfGeneratedStruct(
+        server, "http://yourorganisation.org/union/",
+        UA_TYPES_UNION, UA_TYPES_UNION_COUNT);
+
     UA_ServerConfig *config = UA_Server_getConfig(server);
     ck_assert(config->customDataTypes);
 
-    ck_assert(config->customDataTypes->typesSize == UA_TYPES_UNION2_COUNT);
+    ck_assert(config->customDataTypes->typesSize == UA_TYPES_UNION_COUNT);
 
-    for (const UA_DataType *generatedType = UA_TYPES_UNION2;
-         generatedType != UA_TYPES_UNION2 + UA_TYPES_UNION2_COUNT;
+    for (const UA_DataType *generatedType = UA_TYPES_UNION;
+         generatedType != UA_TYPES_UNION + UA_TYPES_UNION_COUNT;
          generatedType++)
     {
         const UA_DataType *importedType =
             NodesetLoader_getCustomDataType(server, &generatedType->typeId);
         ck_assert(importedType != NULL);
-        typesAreMatching(generatedType, importedType, &UA_TYPES_UNION2[0],
+        typesAreMatching(generatedType, importedType, &UA_TYPES_UNION[0],
                          config->customDataTypes->types);
     }
 }
diff --git a/backends/open62541/tests/dataTypeImport/optionalStruct.c b/backends/open62541/tests/dataTypeImport/optionalStruct.c
index f0d015d4..9b0acbc6 100644
--- a/backends/open62541/tests/dataTypeImport/optionalStruct.c
+++ b/backends/open62541/tests/dataTypeImport/optionalStruct.c
@@ -42,18 +42,26 @@ START_TEST(compareDI)
 {
     ck_assert(NodesetLoader_loadFile(server, nodesetPath, NULL));
 
+    setNamespaceIndexOfGeneratedStruct(
+        server, "http://yourorganisation.org/optionalStruct/",
+        UA_TYPES_OPTIONALSTRUCT, UA_TYPES_OPTIONALSTRUCT_COUNT);
+
     UA_ServerConfig *config = UA_Server_getConfig(server);
     ck_assert(config->customDataTypes);
 
-    ck_assert(config->customDataTypes->typesSize == UA_TYPES_OPTIONALSTRUCT_COUNT);
+    ck_assert(config->customDataTypes->typesSize ==
+              UA_TYPES_OPTIONALSTRUCT_COUNT);
 
     for (const UA_DataType *generatedType = UA_TYPES_OPTIONALSTRUCT;
-         generatedType != UA_TYPES_OPTIONALSTRUCT + UA_TYPES_OPTIONALSTRUCT_COUNT; generatedType++)
+         generatedType !=
+         UA_TYPES_OPTIONALSTRUCT + UA_TYPES_OPTIONALSTRUCT_COUNT;
+         generatedType++)
     {
         const UA_DataType *importedType =
             NodesetLoader_getCustomDataType(server, &generatedType->typeId);
         ck_assert(importedType != NULL);
-        typesAreMatching(generatedType, importedType, &UA_TYPES_OPTIONALSTRUCT[0],
+        typesAreMatching(generatedType, importedType,
+                         &UA_TYPES_OPTIONALSTRUCT[0],
                          config->customDataTypes->types);
     }
 }
diff --git a/backends/open62541/tests/testHelper.h b/backends/open62541/tests/testHelper.h
index 3a95d2eb..1c66c568 100644
--- a/backends/open62541/tests/testHelper.h
+++ b/backends/open62541/tests/testHelper.h
@@ -92,4 +92,18 @@ UA_NodeId getTypeDefinitionId(UA_Server *s, const UA_NodeId targetId)
     UA_BrowseResult_clear(&br);
     return id;
 }
+
+static void setNamespaceIndexOfGeneratedStruct(UA_Server *server,
+                                               const char *namespaceUri,
+                                               UA_DataType *types,
+                                               size_t typesSize)
+{
+    UA_UInt16 nsIdx = UA_Server_addNamespace(server, namespaceUri);
+
+    for (UA_DataType *type = types; type != types + typesSize; type++)
+    {
+        type->typeId.namespaceIndex = nsIdx;
+        type->binaryEncodingId.namespaceIndex = nsIdx;
+    }
+}
 #endif