diff --git a/src/platforms/common/cdcacm.c b/src/platforms/common/cdcacm.c
index ec052e6..69e59fa 100644
--- a/src/platforms/common/cdcacm.c
+++ b/src/platforms/common/cdcacm.c
@@ -50,7 +50,7 @@
 
 static int configured;
 
-static int gdb_uart_dtr = 1;
+static bool gdb_uart_dtr = true;
 
 static void cdcacm_set_modem_state(usbd_device *dev, uint16_t iface, uint8_t ep);
 
@@ -108,7 +108,7 @@ int cdcacm_get_config(void)
 	return configured;
 }
 
-int gdb_uart_get_dtr(void)
+bool gdb_uart_get_dtr(void)
 {
 	return gdb_uart_dtr;
 }
diff --git a/src/platforms/common/cdcacm.h b/src/platforms/common/cdcacm.h
index 9a2f571..5e84324 100644
--- a/src/platforms/common/cdcacm.h
+++ b/src/platforms/common/cdcacm.h
@@ -28,12 +28,13 @@
 #ifndef __CDCACM_H
 #define __CDCACM_H
 
+#include <stdbool.h>
 #include "usb.h"
 
 void cdcacm_set_config(usbd_device *dev, uint16_t wValue);
 /* Returns current usb configuration, or 0 if not configured. */
 int cdcacm_get_config(void);
 
-int gdb_uart_get_dtr(void);
+bool gdb_uart_get_dtr(void);
 
 #endif