diff --git a/Makefile b/Makefile
index d931fc8994..891cda0b27 100644
--- a/Makefile
+++ b/Makefile
@@ -210,6 +210,7 @@ CFLAGS     += $(ARCH_FLAGS) \
               -Wall -Wextra -Wunsafe-loop-optimizations -Wdouble-promotion \
               -ffunction-sections \
               -fdata-sections \
+			  -fno-common \
               -pedantic \
               $(DEVICE_FLAGS) \
               -D_GNU_SOURCE \
diff --git a/src/main/cms/cms.h b/src/main/cms/cms.h
index 18efcec23a..18d73b4cd6 100644
--- a/src/main/cms/cms.h
+++ b/src/main/cms/cms.h
@@ -38,7 +38,8 @@ extern bool cmsInMenu;
 
 // Device management
 bool cmsDisplayPortRegister(displayPort_t *pDisplay);
-displayPort_t *pCurrentDisplay;
+
+extern displayPort_t *pCurrentDisplay;
 
 // For main.c and scheduler
 void cmsInit(void);
diff --git a/src/main/drivers/bus_spi_ll.c b/src/main/drivers/bus_spi_ll.c
index 826be73092..41cf4579b5 100644
--- a/src/main/drivers/bus_spi_ll.c
+++ b/src/main/drivers/bus_spi_ll.c
@@ -36,8 +36,6 @@
 #include "drivers/nvic.h"
 #include "drivers/rcc.h"
 
-spiDevice_t spiDevice[SPIDEV_COUNT];
-
 #ifndef SPI2_SCK_PIN
 #define SPI2_NSS_PIN    PB12
 #define SPI2_SCK_PIN    PB13
diff --git a/src/main/drivers/bus_spi_stdperiph.c b/src/main/drivers/bus_spi_stdperiph.c
index beda822348..86bdb86e51 100644
--- a/src/main/drivers/bus_spi_stdperiph.c
+++ b/src/main/drivers/bus_spi_stdperiph.c
@@ -33,8 +33,6 @@
 #include "drivers/io.h"
 #include "drivers/rcc.h"
 
-spiDevice_t spiDevice[SPIDEV_COUNT];
-
 void spiInitDevice(SPIDevice device)
 {
     spiDevice_t *spi = &(spiDevice[device]);
diff --git a/src/main/drivers/usb_msc_f7xx.c b/src/main/drivers/usb_msc_f7xx.c
index 776e8a47db..27049456ad 100644
--- a/src/main/drivers/usb_msc_f7xx.c
+++ b/src/main/drivers/usb_msc_f7xx.c
@@ -39,6 +39,7 @@
 #include "drivers/io.h"
 #include "drivers/light_led.h"
 #include "drivers/nvic.h"
+#include "drivers/serial_usb_vcp.h"
 #include "drivers/time.h"
 #include "drivers/usb_msc.h"
 
@@ -51,8 +52,6 @@
 #include "usbd_msc.h"
 #include "msc/usbd_storage.h"
 
-USBD_HandleTypeDef USBD_Device;
-
 #define DEBOUNCE_TIME_MS 20
 
 static IO_t mscButton;
diff --git a/src/main/flight/servos.h b/src/main/flight/servos.h
index 409b8c3177..683918663c 100644
--- a/src/main/flight/servos.h
+++ b/src/main/flight/servos.h
@@ -41,7 +41,7 @@ enum {
     INPUT_GIMBAL_PITCH,
     INPUT_GIMBAL_ROLL,
     INPUT_SOURCE_COUNT
-} inputSource_e;
+};
 
 // target servo channels
 typedef enum {
diff --git a/src/main/io/displayport_hott.h b/src/main/io/displayport_hott.h
index 43df02061e..c1e5026905 100644
--- a/src/main/io/displayport_hott.h
+++ b/src/main/io/displayport_hott.h
@@ -19,7 +19,8 @@
 #include "drivers/display.h"
 
 displayPort_t *displayPortHottInit();
-displayPort_t hottDisplayPort;
+
+extern displayPort_t hottDisplayPort;
 
 void hottDisplayportRegister();
 void hottCmsOpen();
diff --git a/src/main/io/displayport_srxl.h b/src/main/io/displayport_srxl.h
index 5547205208..8702cc1b2f 100644
--- a/src/main/io/displayport_srxl.h
+++ b/src/main/io/displayport_srxl.h
@@ -21,4 +21,5 @@
 #pragma once
 
 displayPort_t *displayPortSrxlInit();
-displayPort_t srxlDisplayPort;
+
+extern displayPort_t srxlDisplayPort;
diff --git a/src/main/io/ledstrip.c b/src/main/io/ledstrip.c
index d668c04407..f9eef78df2 100644
--- a/src/main/io/ledstrip.c
+++ b/src/main/io/ledstrip.c
@@ -77,6 +77,10 @@
 
 PG_REGISTER_WITH_RESET_FN(ledStripConfig_t, ledStripConfig, PG_LED_STRIP_CONFIG, 0);
 
+hsvColor_t *colors;
+const modeColorIndexes_t *modeColors;
+specialColorIndexes_t specialColors;
+
 static bool ledStripInitialised = false;
 static bool ledStripEnabled = true;
 
diff --git a/src/main/io/ledstrip.h b/src/main/io/ledstrip.h
index 3f4d3b9840..07641492df 100644
--- a/src/main/io/ledstrip.h
+++ b/src/main/io/ledstrip.h
@@ -157,9 +157,9 @@ typedef struct ledStripConfig_s {
 
 PG_DECLARE(ledStripConfig_t, ledStripConfig);
 
-hsvColor_t *colors;
-const modeColorIndexes_t *modeColors;
-specialColorIndexes_t specialColors;
+extern hsvColor_t *colors;
+extern const modeColorIndexes_t *modeColors;
+extern specialColorIndexes_t specialColors;
 
 #define LF(name) LED_FUNCTION_ ## name
 #define LO(name) LED_FLAG_OVERLAY(LED_OVERLAY_ ## name)
diff --git a/src/main/io/rcdevice_cam.h b/src/main/io/rcdevice_cam.h
index d03a114a7e..f8fc924705 100644
--- a/src/main/io/rcdevice_cam.h
+++ b/src/main/io/rcdevice_cam.h
@@ -43,8 +43,3 @@ void rcdeviceInit(void);
 void rcdeviceUpdate(timeUs_t currentTimeUs);
 
 bool rcdeviceIsEnabled(void);
-
-// used for unit test
-rcdeviceSwitchState_t switchStates[BOXCAMERA3 - BOXCAMERA1 + 1];
-
-void rcdeviceSend5KeyOSDCableSimualtionEvent(rcdeviceCamSimulationKeyEvent_e key);
diff --git a/src/main/vcpf4/usbd_cdc_vcp.c b/src/main/vcpf4/usbd_cdc_vcp.c
index b9cdab30e6..40605aa614 100644
--- a/src/main/vcpf4/usbd_cdc_vcp.c
+++ b/src/main/vcpf4/usbd_cdc_vcp.c
@@ -29,6 +29,8 @@
 #include "stdbool.h"
 #include "drivers/time.h"
 
+__ALIGN_BEGIN USB_OTG_CORE_HANDLE USB_OTG_dev __ALIGN_END;
+
 LINE_CODING g_lc;
 
 extern __IO uint8_t USB_Tx_State;
diff --git a/src/main/vcpf4/usbd_cdc_vcp.h b/src/main/vcpf4/usbd_cdc_vcp.h
index 0a046ad1b7..fc27a6d98e 100644
--- a/src/main/vcpf4/usbd_cdc_vcp.h
+++ b/src/main/vcpf4/usbd_cdc_vcp.h
@@ -34,7 +34,7 @@
 #include "usbd_usr.h"
 #include "usbd_desc.h"
 
-__ALIGN_BEGIN USB_OTG_CORE_HANDLE  USB_OTG_dev __ALIGN_END;
+extern USB_OTG_CORE_HANDLE USB_OTG_dev;
 
 uint32_t CDC_Send_DATA(const uint8_t *ptrBuffer, uint32_t sendLength);
 uint32_t CDC_Send_FreeBytes(void);
diff --git a/src/test/unit/rcdevice_unittest.cc b/src/test/unit/rcdevice_unittest.cc
index 29687cdce5..cb8c072ed1 100644
--- a/src/test/unit/rcdevice_unittest.cc
+++ b/src/test/unit/rcdevice_unittest.cc
@@ -74,6 +74,8 @@ extern "C" {
 
     uint32_t millis(void);
     int minTimeout = 180;
+
+    void rcdeviceSend5KeyOSDCableSimualtionEvent(rcdeviceCamSimulationKeyEvent_e key);
 }
 
 #define MAX_RESPONSES_COUNT 10