diff --git a/Makefile b/Makefile
index 67f58921..95c049e4 100644
--- a/Makefile
+++ b/Makefile
@@ -48,7 +48,7 @@ FIRMWARE_VERSION := $(VERSION_MAJOR).$(VERSION_MINOR)
 # Compiler options
 
 CFLAGS_BASE := -DUSE_MAKE -fsingle-precision-constant -fomit-frame-pointer -ffast-math
-CFLAGS_BASE += -I$(MAIN_INC_DIR) -g3 -O3 -Wall -ffunction-sections
+CFLAGS_BASE += -I$(MAIN_INC_DIR) -g3 -O2 -Wall -ffunction-sections
 
 CFLAGS_COMMON := $(CFLAGS_BASE)
 
diff --git a/Mcu/e230/Inc/blutil.h b/Mcu/e230/Inc/blutil.h
index 9af0d03d..fba23ac9 100644
--- a/Mcu/e230/Inc/blutil.h
+++ b/Mcu/e230/Inc/blutil.h
@@ -58,7 +58,7 @@ static inline void bl_timer_init(void)
 {
     rcu_periph_clock_enable(RCU_TIMER16);
     TIMER_CAR(BL_TIMER) = 0xFFFF;
-    TIMER_PSC(BL_TIMER) = 35;
+    TIMER_PSC(BL_TIMER) = 71;
     timer_auto_reload_shadow_enable(BL_TIMER);
     timer_enable(BL_TIMER);
 }
@@ -124,3 +124,7 @@ static inline void jump_to_application(void)
         "bx	%1	\n"
 	: : "r"(stack_top), "r"(JumpAddress) :);
 }
+
+void SysTick_Handler(void)
+{
+}
diff --git a/Mcu/e230/Src/gd32e23x_it.c b/Mcu/e230/Src/gd32e23x_it.c
index deb4615c..1a3fa780 100644
--- a/Mcu/e230/Src/gd32e23x_it.c
+++ b/Mcu/e230/Src/gd32e23x_it.c
@@ -1,3 +1,5 @@
+#pragma GCC optimize("Os")
+
 extern void transfercomplete();
 extern void PeriodElapsedCallback();
 extern void interruptRoutine();
@@ -21,7 +23,9 @@ int interrupt_time = 0;
 #include "common.h"
 #include "main.h"
 #include "systick.h"
+#ifndef BOOTLOADER
 #include "targets.h"
+#endif
 
 /*!
     \brief      this function handles NMI exception
@@ -60,6 +64,7 @@ void SVC_Handler(void) { }
 */
 void PendSV_Handler(void) { }
 
+#ifndef BOOTLOADER
 /*!
     \brief      this function handles SysTick exception
     \param[in]  none
@@ -151,3 +156,4 @@ void EXTI4_15_IRQHandler(void)
 
     processDshot();
 }
+#endif // BOOTLOADER
diff --git a/e230makefile.mk b/e230makefile.mk
index 6a267eee..ab997476 100644
--- a/e230makefile.mk
+++ b/e230makefile.mk
@@ -5,7 +5,7 @@ TARGETS_$(MCU) := $(call get_targets,$(MCU))
 
 HAL_FOLDER_$(MCU) := $(HAL_FOLDER)/$(call lc,$(MCU))
 
-MCU_$(MCU) := -mfloat-abi=soft -mthumb -march=armv8-m.main
+MCU_$(MCU) := -mfloat-abi=soft -mthumb -mcpu=cortex-m23
 LDSCRIPT_$(MCU) := $(wildcard $(HAL_FOLDER_$(MCU))/*.ld)
 
 SRC_BASE_DIR_$(MCU) := \
@@ -32,4 +32,4 @@ SRC_$(MCU) := $(foreach dir,$(SRC_DIR_$(MCU)),$(wildcard $(dir)/*.[cs]))
 SRC_$(MCU)_BL := $(foreach dir,$(SRC_BASE_DIR_$(MCU)),$(wildcard $(dir)/*.[cs])) \
 	$(HAL_FOLDER_$(MCU))/Src/eeprom.c \
 	$(HAL_FOLDER_$(MCU))/Src/system_gd32e23x.c \
-	$(wildcard $(HAL_FOLDER_$(MCU))/*_it.c)
+	$(wildcard $(HAL_FOLDER_$(MCU))/Src/*_it.c)