diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3c1fd2f52..11122c5f3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -204,7 +204,7 @@ if (SANITIZE_ADDRESS)
     set(CMAKE_STATIC_LINKER_FLAGS "${CMAKE_STATIC_LINKER_FLAGS} -fsanitize=address")
 endif()
 
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wvla -fmax-errors=10 -ffast-math -ftree-vectorize ${EXTRA_FLAGS}")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wvla -Woverloaded-virtual -fmax-errors=10 -ffast-math -ftree-vectorize ${EXTRA_FLAGS}")
 
 ##############################################################################
 # base libraries
diff --git a/plugins/channelrx/demodnfm/nfmdemodgui.cpp b/plugins/channelrx/demodnfm/nfmdemodgui.cpp
index a2d27eed7..1f65583a1 100644
--- a/plugins/channelrx/demodnfm/nfmdemodgui.cpp
+++ b/plugins/channelrx/demodnfm/nfmdemodgui.cpp
@@ -7,7 +7,6 @@
 #include <QDebug>
 
 #include "ui_nfmdemodgui.h"
-#include "dsp/nullsink.h"
 #include "plugin/pluginapi.h"
 #include "util/simpleserializer.h"
 #include "util/db.h"
diff --git a/sdrbase/dsp/nullsink.cpp b/sdrbase/dsp/nullsink.cpp
index 3537d4ff9..592735116 100644
--- a/sdrbase/dsp/nullsink.cpp
+++ b/sdrbase/dsp/nullsink.cpp
@@ -16,7 +16,7 @@ bool NullSink::init(const Message& message __attribute__((unused)))
 	return false;
 }
 
-void NullSink::feed(SampleVector::const_iterator begin __attribute__((unused)), SampleVector::const_iterator end __attribute__((unused)), bool positiveOnly __attribute__((unused)))
+void NullSink::feed(const SampleVector::const_iterator& begin __attribute__((unused)), const SampleVector::const_iterator& end __attribute__((unused)), bool positiveOnly __attribute__((unused)))
 {
 }
 
diff --git a/sdrbase/dsp/nullsink.h b/sdrbase/dsp/nullsink.h
index aef7240eb..f9c75447c 100644
--- a/sdrbase/dsp/nullsink.h
+++ b/sdrbase/dsp/nullsink.h
@@ -13,7 +13,7 @@ public:
 	virtual ~NullSink();
 
 	virtual bool init(const Message& cmd);
-	virtual void feed(SampleVector::const_iterator begin, SampleVector::const_iterator end, bool positiveOnly);
+	virtual void feed(const SampleVector::const_iterator& begin, const SampleVector::const_iterator& end, bool positiveOnly);
 	virtual void start();
 	virtual void stop();
 	virtual bool handleMessage(const Message& message);
diff --git a/sdrgui/webapi/webapiadaptergui.cpp b/sdrgui/webapi/webapiadaptergui.cpp
index a06a5d424..0869cb82c 100644
--- a/sdrgui/webapi/webapiadaptergui.cpp
+++ b/sdrgui/webapi/webapiadaptergui.cpp
@@ -103,7 +103,7 @@ int WebAPIAdapterGUI::instanceSummary(
 }
 
 int WebAPIAdapterGUI::instanceDelete(
-        SWGSDRangel::SWGInstanceSummaryResponse& response __attribute__((unused)),
+        SWGSDRangel::SWGSuccessResponse& response __attribute__((unused)),
         SWGSDRangel::SWGErrorResponse& error)
 {
     *error.getMessage() = QString("Not supported in GUI instance");
diff --git a/sdrgui/webapi/webapiadaptergui.h b/sdrgui/webapi/webapiadaptergui.h
index 18a91ae5b..5b5891d91 100644
--- a/sdrgui/webapi/webapiadaptergui.h
+++ b/sdrgui/webapi/webapiadaptergui.h
@@ -36,7 +36,7 @@ public:
             SWGSDRangel::SWGErrorResponse& error);
 
     virtual int instanceDelete(
-            SWGSDRangel::SWGInstanceSummaryResponse& response,
+            SWGSDRangel::SWGSuccessResponse& response,
             SWGSDRangel::SWGErrorResponse& error);
 
     virtual int instanceDevices(