diff --git a/firmware/config/boards/proteus/board.mk b/firmware/config/boards/proteus/board.mk
index 0aba58bf19..36f08789d3 100644
--- a/firmware/config/boards/proteus/board.mk
+++ b/firmware/config/boards/proteus/board.mk
@@ -21,6 +21,9 @@ DDEFS += -DSTM32_ADC_USE_ADC3=TRUE
 DDEFS += -DEFI_SOFTWARE_KNOCK=TRUE
 DDEFS += -DEFI_CONSOLE_TX_BRAIN_PIN=GPIO_UNASSIGNED -DEFI_CONSOLE_RX_BRAIN_PIN=GPIO_UNASSIGNED
 
+# USB mass storage support
+DDEFS += -DHAL_USE_COMMUNITY=TRUE -DHAL_USE_USB_MSD=TRUE
+
 # We are running on Proteus hardware!
 DDEFS += -DHW_PROTEUS=1
 
diff --git a/firmware/config/stm32f4ems/efifeatures.h b/firmware/config/stm32f4ems/efifeatures.h
index a7c98f7a5a..39f4c350e3 100644
--- a/firmware/config/stm32f4ems/efifeatures.h
+++ b/firmware/config/stm32f4ems/efifeatures.h
@@ -37,7 +37,9 @@
 
 #define EFI_HPFP TRUE
 
+#ifndef HAL_USE_USB_MSD
 #define HAL_USE_USB_MSD FALSE
+#endif
 
 #define EFI_ENABLE_CRITICAL_ENGINE_STOP TRUE
 #define EFI_ENABLE_ENGINE_WARNING TRUE
diff --git a/firmware/hw_layer/mmc_card.cpp b/firmware/hw_layer/mmc_card.cpp
index d087ddc4c1..b1e077e197 100644
--- a/firmware/hw_layer/mmc_card.cpp
+++ b/firmware/hw_layer/mmc_card.cpp
@@ -352,6 +352,13 @@ static const scsi_inquiry_response_t scsi_inquiry_response = {
     "SD Card",
     {'v',CH_KERNEL_MAJOR+'0','.',CH_KERNEL_MINOR+'0'}
 };
+
+static binary_semaphore_t usbConnectedSemaphore;
+
+void onUsbConnectedNotifyMmcI() {
+	chBSemSignalI(&usbConnectedSemaphore);
+}
+
 #endif /* HAL_USE_USB_MSD */
 
 /*
@@ -397,18 +404,25 @@ static bool mountMmc() {
 	auto cardBlockDevice = initializeMmcBlockDevice();
 
 #if HAL_USE_USB_MSD
+	// Wait for the USB stack to wake up, or a 5 second timeout, whichever occurs first
+	msg_t usbResult = chBSemWaitTimeout(&usbConnectedSemaphore, TIME_MS2I(5000));
+
+	bool hasUsb = usbResult == MSG_OK;
+
 	msdObjectInit(&USBMSD1);
-	
-	if (cardBlockDevice) {
+
+	// If we have a device AND USB is connected, mount the card to USB, otherwise
+	// mount the null device and try to mount the filesystem ourselves
+	if (cardBlockDevice && hasUsb) {
 		// Mount the real card to USB
 		msdStart(&USBMSD1, usb_driver, cardBlockDevice, blkbuf, &scsi_inquiry_response, NULL);
+
+		// At this point we're done: don't try to write files ourselves
+		return false;
 	} else {
 		// Mount a  "no media" device to USB
 		msdMountNullDevice(&USBMSD1, usb_driver, blkbuf, &scsi_inquiry_response);
 	}
-
-	// TODO: local mount and log if USB not connected
-	return false;
 #endif
 
 	// if no card, don't try to mount FS
@@ -416,7 +430,7 @@ static bool mountMmc() {
 		return false;
 	}
 
-	// if Ok - mount FS now
+	// We were able to connect the SD card, mount the filesystem
 	memset(&MMC_FS, 0, sizeof(FATFS));
 	if (f_mount(&MMC_FS, "/", 1) == FR_OK) {
 		sdStatus = SD_STATE_MOUNTED;
@@ -473,7 +487,12 @@ static SdLogBufferWriter logBuffer MAIN_RAM;
 
 static THD_FUNCTION(MMCmonThread, arg) {
 	(void)arg;
-	chRegSetThreadName("MMC_Monitor");
+	chRegSetThreadName("MMC Card Logger");
+
+	if (!mountMmc()) {
+		// no card present (or mounted via USB), don't do internal logging
+		return;
+	}
 
 	while (true) {
 		// if the SPI device got un-picked somehow, cancel SD card
@@ -509,10 +528,9 @@ bool isSdCardAlive(void) {
 void initMmcCard(void) {
 	logName[0] = 0;
 
-	if (!mountMmc()) {
-		// no card present, don't start thread
-		return;
-	}
+#if HAL_USE_USB_MSD
+	chBSemObjectInit(&usbConnectedSemaphore, true);
+#endif
 
 	chThdCreateStatic(mmcThreadStack, sizeof(mmcThreadStack), LOWPRIO, (tfunc_t)(void*) MMCmonThread, NULL);
 
diff --git a/firmware/hw_layer/mmc_card.h b/firmware/hw_layer/mmc_card.h
index d0eddd5a7a..5ef1a0ecac 100644
--- a/firmware/hw_layer/mmc_card.h
+++ b/firmware/hw_layer/mmc_card.h
@@ -9,6 +9,7 @@
 
 #pragma once
 
+#ifdef __cplusplus
 #include "tunerstudio_io.h"
 
 #define DOT_MLG ".mlg"
@@ -25,3 +26,7 @@ void handleTsW(ts_channel_s *tsChannel, char *input);
 extern spi_device_e mmcSpiDevice;
 #define LOCK_SD_SPI lockSpi(mmcSpiDevice)
 #define UNLOCK_SD_SPI unlockSpi(mmcSpiDevice)
+
+extern "C"
+#endif
+void onUsbConnectedNotifyMmcI(void);
diff --git a/firmware/hw_layer/ports/stm32/serial_over_usb/usbcfg.c b/firmware/hw_layer/ports/stm32/serial_over_usb/usbcfg.c
index 44845aa0e1..6923b7dd8a 100644
--- a/firmware/hw_layer/ports/stm32/serial_over_usb/usbcfg.c
+++ b/firmware/hw_layer/ports/stm32/serial_over_usb/usbcfg.c
@@ -17,6 +17,7 @@
 
 #include "global.h"
 #include "os_access.h"
+#include "mmc_card.h"
 
 #if HAL_USE_SERIAL_USB
 
@@ -376,6 +377,11 @@ static void usb_event(USBDriver *usbp, usbevent_t event) {
     /* Resetting the state of the CDC subsystem.*/
     sduConfigureHookI(&SDU1);
 
+    #if HAL_USE_USB_MSD
+        // Tell the MMC thread to wake up and mount the card as a USB device
+        onUsbConnectedNotifyMmcI();
+    #endif
+
     chSysUnlockFromISR();
     return;
   case USB_EVENT_RESET: