diff --git a/NuEVI/settings.cpp b/NuEVI/settings.cpp
index d6d92d6..2403a97 100644
--- a/NuEVI/settings.cpp
+++ b/NuEVI/settings.cpp
@@ -393,7 +393,8 @@ void configShowMessage(const char* message) {
 uint8_t* sysex_rcv_buffer = NULL;
 uint16_t sysex_buf_size = 0;
 
-void handleSysexChunk(const uint8_t *data, const uint16_t length, const uint8_t last) {
+
+void handleSysexChunk(const uint8_t *data, uint16_t length, bool last) {
   uint16_t pos;
 
   if(!sysex_rcv_buffer) {
@@ -423,7 +424,7 @@ void handleSysexChunk(const uint8_t *data, const uint16_t length, const uint8_t
 }
 
 
-void handleSysex(const uint8_t *data, const unsigned int length) {
+void handleSysex(uint8_t *data, unsigned int length) {
   //Note: Sysex data as received here contains sysex start and end markers (0xF0 and 0xF7)
 
   //Too short to even contain a 3-byte vendor id is not for us.
diff --git a/NuEVI/settings.h b/NuEVI/settings.h
index 636a5bb..15fe0c6 100644
--- a/NuEVI/settings.h
+++ b/NuEVI/settings.h
@@ -133,8 +133,9 @@ void sendSysexSettings();
 void sendSysexMessage(const char* messageCode);
 void sendSysexVersion();
 
-void handleSysex(const uint8_t *data, const unsigned int length);
-void handleSysexChunk(const uint8_t *data, const uint16_t length, const bool last);
+void handleSysex(uint8_t *data, unsigned int length);
+void handleSysexChunk(const uint8_t *data, uint16_t length, bool last);
+
 uint32_t crc32(const uint8_t *message, const size_t length);
 
 void configInitScreen();
diff --git a/simulation/include/Arduino.h b/simulation/include/Arduino.h
index ba160fe..534f404 100644
--- a/simulation/include/Arduino.h
+++ b/simulation/include/Arduino.h
@@ -86,7 +86,7 @@ public:
 	void sendSysEx(uint16_t length, const uint8_t *data, bool hasTerm=false, uint8_t cable=0);
 	bool read(uint8_t channel=0);
 	void setHandleSystemExclusive(void (*fptr) (const uint8_t *array, unsigned int size));
-	void setHandleSystemExclusive(void (*fptr) (const uint8_t *data, uint16_t length, uint8_t complete));
+	void setHandleSystemExclusive(void (*fptr) (const uint8_t *data, uint16_t length, bool complete));
 
 	void receiveMidiData(const uint8_t *data, const uint16_t length); //Send midi data "into simulator"
 private:
diff --git a/simulation/src/simusbmidi.cpp b/simulation/src/simusbmidi.cpp
index dfa5661..e22cea7 100644
--- a/simulation/src/simusbmidi.cpp
+++ b/simulation/src/simusbmidi.cpp
@@ -134,12 +134,12 @@ void SimUsbMidi::receiveMidiData(const uint8_t *data, const uint16_t length) {
 	}
 }
 
-//Regular sysex handler. For some reason the data pointer is not const, but we'll set it as such to not be dumb.
+//MIDI SysEx handlers. Choice of data types is a bit odd, but done to match Arduino/Teensy libraries
 void SimUsbMidi::setHandleSystemExclusive(void (*fptr) (const uint8_t *array, unsigned int size)) {
 	this->usb_midi_handleSysExComplete = fptr;
 }
 
 //"Chunked" sysex handler (teensy extension), for large messages
-void SimUsbMidi::setHandleSystemExclusive(void (*fptr) (const uint8_t *array, uint16_t size, uint8_t last)) {
-	this->usb_midi_handleSysExPartial = fptr;
+void SimUsbMidi::setHandleSystemExclusive(void (*fptr) (const uint8_t *array, uint16_t size, bool last)) {
+	this->usb_midi_handleSysExPartial = (void (*)(const uint8_t *, uint16_t, uint8_t))fptr;
 }