diff --git a/software/linux/Makefile b/software/linux/Makefile
index 2785700..f24f417 100644
--- a/software/linux/Makefile
+++ b/software/linux/Makefile
@@ -5,7 +5,7 @@ OBJDIR = bin
 
 CC = clang
 
-CFLAGS =  -I ../sss7core/ -Os -Wall -Wstrict-prototypes -fPIC
+CFLAGS =  -DSSS7_THREADED -I ../sss7core/ -Os -Wall -Wstrict-prototypes -fPIC
 LDFLAGS = -pthread -Wl,--gc-sections
 
 all: start $(OBJDIR)/libsss7.so $(OBJDIR)/test
diff --git a/software/sss7core/sss7.c b/software/sss7core/sss7.c
index 4dc58ca..5120bf6 100644
--- a/software/sss7core/sss7.c
+++ b/software/sss7core/sss7.c
@@ -85,7 +85,7 @@ void sss7_process_rx(void) {
 	uint8_t next_buffer_write = 0;
 	sss7_timeout_counter = 0;
 
-	switch(sss7_state) {
+	switch((int) sss7_state) {
 		case SSS7_IDLE:
 			if(byte == SSS7_HEADER[0]) {
 				sss7_state = SSS7_RX_HEADER;
@@ -141,7 +141,7 @@ void sss7_process_rx(void) {
 void sss7_process_tx(void) {
 	if(sss7_tx_last_ack) {
 		uint8_t byte;
-		switch(sss7_state) {
+		switch((int) sss7_state) {
 			case SSS7_TX_HEADER:
 				sss7_send_byte(SSS7_HEADER[1]);
 				sss7_state = SSS7_TX_PAYLOAD;
@@ -178,7 +178,7 @@ void sss7_process_ticks(uint16_t ticks) {
 		sss7_timeout_counter = sss7_timeout_counter + ticks;
 
 		if(sss7_timeout_counter > sss7_timeout) {
-			switch(sss7_state) {
+			switch((int) sss7_state) {
 				case SSS7_TX_HEADER:
 				case SSS7_TX_PAYLOAD:
 				case SSS7_TX_CRC:
diff --git a/software/sss7core/sss7.h b/software/sss7core/sss7.h
index db18204..3370bee 100644
--- a/software/sss7core/sss7.h
+++ b/software/sss7core/sss7.h
@@ -7,7 +7,9 @@ extern "C" {
 
 #include <stdint.h>
 
-#ifndef sss7_shared_modfier
+#ifdef SSS7_THREADED
+#define sss7_shared_modfier _Atomic
+#else
 #define sss7_shared_modfier volatile
 #endif