diff --git a/os/various/syscalls.c b/os/various/syscalls.c
index 7cc98b5ea..252028c7f 100644
--- a/os/various/syscalls.c
+++ b/os/various/syscalls.c
@@ -133,6 +133,7 @@ int _close_r(struct _reent *r, int file)
 
 caddr_t _sbrk_r(struct _reent *r, int incr)
 {
+#if CH_USE_MEMCORE
   void *p;
 
   chDbgCheck(incr > 0, "_sbrk_r");
@@ -144,6 +145,10 @@ caddr_t _sbrk_r(struct _reent *r, int incr)
     return (caddr_t)-1;
   }
   return (caddr_t)p;
+#else
+  __errno_r(r) = ENOMEM;
+  return (caddr_t)-1;
+#endif
 }
 
 /***************************************************************************/
diff --git a/readme.txt b/readme.txt
index 9a6f333a5..307d9d800 100644
--- a/readme.txt
+++ b/readme.txt
@@ -83,6 +83,8 @@
 *****************************************************************************
 
 *** 2.5.1 ***
+- FIX: Fixed compilation issue in syscalls.c (bug 3576771)(backported
+  to 2.4.3).
 - FIX: Fixed Typos in STM32F0xx EXT driver (bug 3576193).
 - FIX: Fixed STM32F10X_CL: Wrong CAN1 interrupt number definitions (bug
   3575766).