diff --git a/3rd-party/segger-rtt/SEGGER_RTT_Syscalls_GCC.c b/3rd-party/segger-rtt/SEGGER_RTT_Syscalls_GCC.c
index 27292de50..c573ed764 100644
--- a/3rd-party/segger-rtt/SEGGER_RTT_Syscalls_GCC.c
+++ b/3rd-party/segger-rtt/SEGGER_RTT_Syscalls_GCC.c
@@ -59,12 +59,16 @@ Purpose : Low-level functions for using printf() via RTT in GCC.
 Revision: $Rev: 4351 $
 ----------------------------------------------------------------------
 */
+
+#include "btstack_config.h"
+
+#ifdef ENABLE_SEGGER_RTT
+
 #if (defined __GNUC__) && !(defined __SES_ARM) && !(defined __CROSSWORKS_ARM)
 
 #include <reent.h>  // required for _write_r
 #include "SEGGER_RTT.h"
 
-
 /*********************************************************************
 *
 *       Types
@@ -84,7 +88,7 @@ struct _reent;
 **********************************************************************
 */
 int _write(int file, char *ptr, int len);
-int _write_r(struct _reent *r, int file, const void *ptr, int len);
+_ssize_t _write_r(struct _reent *r, int file, const void *ptr, size_t len);
 
 /*********************************************************************
 *
@@ -119,12 +123,14 @@ int _write(int file, char *ptr, int len) {
 *   including stdout.
 *   Write data via RTT.
 */
-int _write_r(struct _reent *r, int file, const void *ptr, int len) {
+_ssize_t _write_r(struct _reent *r, int file, const void *ptr, size_t len) {
   (void) file;  /* Not used, avoid warning */
   (void) r;     /* Not used, avoid warning */
   SEGGER_RTT_Write(0, ptr, len);
   return len;
 }
 
+#endif
+
 #endif
 /****** End Of File *************************************************/