diff --git a/libraries/AP_HAL_ChibiOS/Scheduler.h b/libraries/AP_HAL_ChibiOS/Scheduler.h
index ac862002e5..20ca9754a8 100644
--- a/libraries/AP_HAL_ChibiOS/Scheduler.h
+++ b/libraries/AP_HAL_ChibiOS/Scheduler.h
@@ -54,7 +54,7 @@
 #endif
 
 #ifndef TIMER_THD_WA_SIZE
-#define TIMER_THD_WA_SIZE   2048
+#define TIMER_THD_WA_SIZE   1536
 #endif
 
 #ifndef RCIN_THD_WA_SIZE
@@ -66,7 +66,7 @@
 #endif
 
 #ifndef STORAGE_THD_WA_SIZE
-#define STORAGE_THD_WA_SIZE 2048
+#define STORAGE_THD_WA_SIZE 1536
 #endif
 
 #ifndef MONITOR_THD_WA_SIZE
diff --git a/libraries/AP_HAL_ChibiOS/UARTDriver.cpp b/libraries/AP_HAL_ChibiOS/UARTDriver.cpp
index 8a2961f240..9ba8b0130e 100644
--- a/libraries/AP_HAL_ChibiOS/UARTDriver.cpp
+++ b/libraries/AP_HAL_ChibiOS/UARTDriver.cpp
@@ -65,7 +65,7 @@ UARTDriver *UARTDriver::uart_drivers[UART_MAX_DRIVERS];
 #endif
 
 #ifndef HAL_UART_STACK_SIZE
-#define HAL_UART_STACK_SIZE 2048
+#define HAL_UART_STACK_SIZE 1536
 #endif
 
 UARTDriver::UARTDriver(uint8_t _serial_num) :
diff --git a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
index 9b4c633e43..4bccebeb6a 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
+++ b/libraries/AP_HAL_ChibiOS/hwdef/scripts/chibios_hwdef.py
@@ -679,7 +679,7 @@ def write_mcu_config(f):
     if get_config('PROCESS_STACK', required=False):
         env_vars['PROCESS_STACK'] = get_config('PROCESS_STACK')
     else:
-        env_vars['PROCESS_STACK'] = "0x2000"
+        env_vars['PROCESS_STACK'] = "0x1C00"
 
     # MAIN_STACK is location of initial stack on startup and is also the stack
     # used for slow interrupts. It needs to be big enough for maximum interrupt