diff --git a/CMakeLists.txt b/CMakeLists.txt
index d88f37de..ad2cbd34 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -137,6 +137,13 @@ add_definitions(-DCONFIG_MMS_SUPPORT_TLS=1)
 
 endif(WITH_MBEDTLS)
 
+include(CheckCCompilerFlag)
+
+check_c_compiler_flag("-Wredundant-decls" SUPPORT_REDUNDANT_DECLS)
+if (SUPPORT_REDUNDANT_DECLS)
+    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wredundant-decls")
+endif(SUPPORT_REDUNDANT_DECLS)
+
 # write the detected stuff to this file
 configure_file(
     ${CMAKE_CURRENT_LIST_DIR}/config/stack_config.h.cmake
diff --git a/examples/iec61850_9_2_LE_example/iec61850_9_2_LE_example.c b/examples/iec61850_9_2_LE_example/iec61850_9_2_LE_example.c
index 34aba48e..a68ef7ce 100644
--- a/examples/iec61850_9_2_LE_example/iec61850_9_2_LE_example.c
+++ b/examples/iec61850_9_2_LE_example/iec61850_9_2_LE_example.c
@@ -34,9 +34,6 @@
 /* Include the generated header with the model access handles */
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 static int svcbEnabled = 1;
 
diff --git a/examples/server_example_61400_25/server_example_61400_25.c b/examples/server_example_61400_25/server_example_61400_25.c
index 7c4c0319..118f13e9 100644
--- a/examples/server_example_61400_25/server_example_61400_25.c
+++ b/examples/server_example_61400_25/server_example_61400_25.c
@@ -29,9 +29,6 @@
 
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static IedServer iedServer;
 
 static int running = 0;
diff --git a/examples/server_example_basic_io/server_example_basic_io.c b/examples/server_example_basic_io/server_example_basic_io.c
index 66914aa1..dea67a69 100644
--- a/examples/server_example_basic_io/server_example_basic_io.c
+++ b/examples/server_example_basic_io/server_example_basic_io.c
@@ -15,9 +15,6 @@
 
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 static IedServer iedServer = NULL;
 
diff --git a/examples/server_example_complex_array/server_example_ca.c b/examples/server_example_complex_array/server_example_ca.c
index c70eb7b6..a2406639 100644
--- a/examples/server_example_complex_array/server_example_ca.c
+++ b/examples/server_example_complex_array/server_example_ca.c
@@ -14,9 +14,6 @@
 
 #include <assert.h>
 
-/* import IEC 61850 device model created from ICD-File */
-extern IedModel iedModel;
-
 static int running = 0;
 
 static void
diff --git a/examples/server_example_control/server_example_control.c b/examples/server_example_control/server_example_control.c
index 364c20c6..6159cdda 100644
--- a/examples/server_example_control/server_example_control.c
+++ b/examples/server_example_control/server_example_control.c
@@ -12,9 +12,6 @@
 
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 static IedServer iedServer = NULL;
 
diff --git a/examples/server_example_deadband/server_example_deadband.c b/examples/server_example_deadband/server_example_deadband.c
index a7d18bde..044b72e8 100644
--- a/examples/server_example_deadband/server_example_deadband.c
+++ b/examples/server_example_deadband/server_example_deadband.c
@@ -15,9 +15,6 @@
 
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 static IedServer iedServer = NULL;
 
diff --git a/examples/server_example_files/server_example_files.c b/examples/server_example_files/server_example_files.c
index 78956c55..702eed59 100644
--- a/examples/server_example_files/server_example_files.c
+++ b/examples/server_example_files/server_example_files.c
@@ -14,9 +14,6 @@
 
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 static IedServer iedServer = NULL;
 
diff --git a/examples/server_example_goose/server_example_goose.c b/examples/server_example_goose/server_example_goose.c
index ef0db87c..01dfe1ec 100644
--- a/examples/server_example_goose/server_example_goose.c
+++ b/examples/server_example_goose/server_example_goose.c
@@ -14,9 +14,6 @@
 
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 static IedServer iedServer = NULL;
 
diff --git a/examples/server_example_logging/server_example_logging.c b/examples/server_example_logging/server_example_logging.c
index 96b71bb9..01ad5ae2 100644
--- a/examples/server_example_logging/server_example_logging.c
+++ b/examples/server_example_logging/server_example_logging.c
@@ -20,9 +20,6 @@
 LogStorage
 SqliteLogStorage_createInstance(const char* filename);
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 static IedServer iedServer = NULL;
 
diff --git a/examples/server_example_password_auth/server_example_password_auth.c b/examples/server_example_password_auth/server_example_password_auth.c
index 149c6fbb..2327923f 100644
--- a/examples/server_example_password_auth/server_example_password_auth.c
+++ b/examples/server_example_password_auth/server_example_password_auth.c
@@ -19,10 +19,7 @@
 #include <signal.h>
 #include <stdlib.h>
 #include <stdio.h>
-#include "../server_example_password_auth/static_model.h"
-
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
+#include "static_model.h"
 
 static int running = 0;
 
diff --git a/examples/server_example_service_tracking/server_example_service_tracking.c b/examples/server_example_service_tracking/server_example_service_tracking.c
index f2532357..3d34df19 100644
--- a/examples/server_example_service_tracking/server_example_service_tracking.c
+++ b/examples/server_example_service_tracking/server_example_service_tracking.c
@@ -13,9 +13,6 @@
 
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 static IedServer iedServer = NULL;
 
diff --git a/examples/server_example_setting_groups/server_example_sg.c b/examples/server_example_setting_groups/server_example_sg.c
index e319b26d..4466c1ad 100644
--- a/examples/server_example_setting_groups/server_example_sg.c
+++ b/examples/server_example_setting_groups/server_example_sg.c
@@ -12,9 +12,6 @@
 /* Include the generated header with the model access handles */
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static IedServer iedServer;
 static int running = 0;
 
diff --git a/examples/server_example_simple/server_example_simple.c b/examples/server_example_simple/server_example_simple.c
index 5bd97693..5815b695 100644
--- a/examples/server_example_simple/server_example_simple.c
+++ b/examples/server_example_simple/server_example_simple.c
@@ -29,9 +29,6 @@
 
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 
 void
diff --git a/examples/server_example_substitution/server_example_substitution.c b/examples/server_example_substitution/server_example_substitution.c
index 2f41d892..c8292dee 100644
--- a/examples/server_example_substitution/server_example_substitution.c
+++ b/examples/server_example_substitution/server_example_substitution.c
@@ -17,9 +17,6 @@
 
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 static IedServer iedServer = NULL;
 
diff --git a/examples/server_example_threadless/server_example_threadless.c b/examples/server_example_threadless/server_example_threadless.c
index d01efe28..ae63ce62 100644
--- a/examples/server_example_threadless/server_example_threadless.c
+++ b/examples/server_example_threadless/server_example_threadless.c
@@ -13,9 +13,6 @@
 
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 static IedServer iedServer = NULL;
 
diff --git a/examples/server_example_write_handler/server_example_write_handler.c b/examples/server_example_write_handler/server_example_write_handler.c
index d1d2295e..49151f06 100644
--- a/examples/server_example_write_handler/server_example_write_handler.c
+++ b/examples/server_example_write_handler/server_example_write_handler.c
@@ -10,9 +10,6 @@
 
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 static IedServer iedServer = NULL;
 
diff --git a/examples/tls_server_example/tls_server_example.c b/examples/tls_server_example/tls_server_example.c
index d5fdf211..08bfd662 100644
--- a/examples/tls_server_example/tls_server_example.c
+++ b/examples/tls_server_example/tls_server_example.c
@@ -13,9 +13,6 @@
 
 #include "static_model.h"
 
-/* import IEC 61850 device model created from SCL-File */
-extern IedModel iedModel;
-
 static int running = 0;
 static IedServer iedServer = NULL;
 
diff --git a/src/iec61850/inc_private/ied_connection_private.h b/src/iec61850/inc_private/ied_connection_private.h
index 619da24c..e571ca8e 100644
--- a/src/iec61850/inc_private/ied_connection_private.h
+++ b/src/iec61850/inc_private/ied_connection_private.h
@@ -1,7 +1,7 @@
 /*
  *  ied_connection_private.h
  *
- *  Copyright 2013-2018 Michael Zillgith
+ *  Copyright 2013-2022 Michael Zillgith
  *
  *  This file is part of libIEC61850.
  *
@@ -145,16 +145,4 @@ controlObjectClient_invokeCommandTerminationHandler(ControlObjectClient self);
 LIB61850_INTERNAL void
 ControlObjectClient_setLastApplError(ControlObjectClient self, LastApplError lastAppIError);
 
-/* some declarations that are shared with server side ! */
-
-LIB61850_INTERNAL char*
-MmsMapping_createMmsVariableNameFromObjectReference(const char* objectReference, FunctionalConstraint fc, char* buffer);
-
-
-LIB61850_INTERNAL char*
-MmsMapping_varAccessSpecToObjectReference(MmsVariableAccessSpecification* varAccessSpec);
-
-LIB61850_INTERNAL MmsVariableAccessSpecification*
-MmsMapping_ObjectReferenceToVariableAccessSpec(char* objectReference);
-
 #endif /* IED_CONNECTION_PRIVATE_H_ */
diff --git a/src/iec61850/server/mms_mapping/mms_mapping.c b/src/iec61850/server/mms_mapping/mms_mapping.c
index a027a281..81ac3cbc 100644
--- a/src/iec61850/server/mms_mapping/mms_mapping.c
+++ b/src/iec61850/server/mms_mapping/mms_mapping.c
@@ -69,12 +69,10 @@ typedef struct
 } SettingGroup;
 
 #if (CONFIG_IEC61850_CONTROL_SERVICE == 1)
-MmsValue*
-Control_readAccessControlObject(MmsMapping* self, MmsDomain* domain, char* variableIdOrig,
-        MmsServerConnection connection, bool isDirectAccess);
 
 bool
 ControlObject_unselect(ControlObject* self, MmsServerConnection connection, MmsMapping* mmsMapping);
+
 #endif
 
 void /* Create PHYCOMADDR ACSI type instance */
diff --git a/src/mms/inc/mms_client_connection.h b/src/mms/inc/mms_client_connection.h
index 5126dbb9..70bedc28 100644
--- a/src/mms/inc/mms_client_connection.h
+++ b/src/mms/inc/mms_client_connection.h
@@ -1036,6 +1036,11 @@ LIB61850_API void
 MmsConnection_identifyAsync(MmsConnection self, uint32_t* usedInvokeId, MmsError* mmsError,
         MmsConnection_IdentifyHandler handler, void* parameter);
 
+/**
+ * \brief Destroy (free) an MmsServerIdentity object
+ *
+ * \param self the object to destroy
+ */
 LIB61850_API void
 MmsServerIdentity_destroy(MmsServerIdentity* self);
 
@@ -1285,14 +1290,6 @@ LIB61850_API void
 MmsConnection_readJournalStartAfterAsync(MmsConnection self, uint32_t* usedInvokeId, MmsError* mmsError, const char* domainId, const char* itemId,
         MmsValue* timeSpecification, MmsValue* entrySpecification, MmsConnection_ReadJournalHandler handler, void* parameter);
 
-/**
- * \brief Destroy (free) an MmsServerIdentity object
- *
- * \param self the object to destroy
- */
-LIB61850_API void
-MmsServerIdentity_destroy(MmsServerIdentity* self);
-
 /**@}*/
 
 #ifdef __cplusplus
diff --git a/src/mms/inc_private/ber_encoder.h b/src/mms/inc_private/ber_encoder.h
index 9f88b168..48cd2bc6 100644
--- a/src/mms/inc_private/ber_encoder.h
+++ b/src/mms/inc_private/ber_encoder.h
@@ -64,9 +64,6 @@ BerEncoder_encodeUInt32WithTL(uint8_t tag, uint32_t value, uint8_t* buffer, int
 LIB61850_INTERNAL int
 BerEncoder_encodeBitString(uint8_t tag, int bitStringSize, uint8_t* bitString, uint8_t* buffer, int bufPos);
 
-LIB61850_INTERNAL int
-BerEncoder_determineEncodedBitStringSize(int bitStringSize);
-
 LIB61850_INTERNAL int
 BerEncoder_encodeFloat(uint8_t* floatValue, uint8_t formatWidth, uint8_t exponentWidth,
         uint8_t* buffer, int bufPos);
diff --git a/src/mms/inc_private/mms_server_internal.h b/src/mms/inc_private/mms_server_internal.h
index 62bcc81f..404b7030 100644
--- a/src/mms/inc_private/mms_server_internal.h
+++ b/src/mms/inc_private/mms_server_internal.h
@@ -1,7 +1,7 @@
 /*
  *  mms_server_internal.h
  *
- *  Copyright 2013-2018 Michael Zillgith
+ *  Copyright 2013-2022 Michael Zillgith
  *
  *  This file is part of libIEC61850.
  *
@@ -260,9 +260,6 @@ mmsServer_handleReadRequest(
 LIB61850_INTERNAL MmsPdu_t*
 mmsServer_createConfirmedResponse(uint32_t invokeId);
 
-LIB61850_INTERNAL void
-mmsMsg_createServiceErrorPdu(uint32_t invokeId, ByteBuffer* response, MmsError errorType);
-
 LIB61850_INTERNAL void
 mmsMsg_createInitiateErrorPdu(ByteBuffer* response, uint8_t initiateErrorCode);
 
@@ -415,9 +412,6 @@ LIB61850_INTERNAL void
 mmsServer_createMmsWriteResponse(MmsServerConnection connection,
         uint32_t invokeId, ByteBuffer* response, int numberOfItems, MmsDataAccessError* accessResults);
 
-LIB61850_INTERNAL void
-mmsMsg_createMmsRejectPdu(uint32_t* invokeId, int reason, ByteBuffer* response);
-
 LIB61850_INTERNAL MmsError
 mmsServer_callVariableListChangedHandler(bool create, MmsVariableListType listType, MmsDomain* domain,
         char* listName, MmsServerConnection connection);