diff --git a/radio/src/opentx.cpp b/radio/src/opentx.cpp
index 892358f72..2daf22cbe 100644
--- a/radio/src/opentx.cpp
+++ b/radio/src/opentx.cpp
@@ -3321,7 +3321,7 @@ uint16_t stack_free(uint8_t tid)
   for (; i<size; i++)
     if (stack[i] != 0x55555555)
       break;
-  return i*4;
+  return i;
 }
 #else
 extern unsigned char __bss_end ;
diff --git a/radio/src/targets/sky9x/syscalls.c b/radio/src/targets/sky9x/syscalls.c
index 0c9ddfe44..32472759d 100644
--- a/radio/src/targets/sky9x/syscalls.c
+++ b/radio/src/targets/sky9x/syscalls.c
@@ -68,7 +68,7 @@ extern int _getpid ( void ) ;
 unsigned char *heap = (unsigned char *)&_end;
 extern caddr_t _sbrk(int nbytes)
 {
-  if (heap + nbytes < RAM_END-4096) {
+  if (heap + nbytes < RAM_END-8192) {
     unsigned char *prev_heap = heap;
     heap += nbytes;
     return (caddr_t) prev_heap;