diff --git a/firmware/drivers/ata_mmc.c b/firmware/drivers/ata_mmc.c
index 260418c694..b528bdb1e3 100644
--- a/firmware/drivers/ata_mmc.c
+++ b/firmware/drivers/ata_mmc.c
@@ -91,7 +91,7 @@ long last_disk_activity = -1;
 static struct mutex mmc_mutex;
 
 #ifdef HAVE_HOTSWAP
-static char mmc_stack[DEFAULT_STACK_SIZE];
+static long mmc_stack[DEFAULT_STACK_SIZE/sizeof(long)];
 static const char mmc_thread_name[] = "mmc";
 static struct event_queue mmc_queue;
 #endif
diff --git a/firmware/powermgmt.c b/firmware/powermgmt.c
index 46f9d4df3f..cb9fb53fcb 100644
--- a/firmware/powermgmt.c
+++ b/firmware/powermgmt.c
@@ -164,7 +164,7 @@ void enable_trickle_charge(bool on)
 }
 #endif /* HAVE_CHARGE_CTRL */
 
-static char power_stack[DEFAULT_STACK_SIZE];
+static long power_stack[DEFAULT_STACK_SIZE/sizeof(long)];
 static const char power_thread_name[] = "power";
 
 static int poweroff_timeout = 0;
diff --git a/firmware/usb.c b/firmware/usb.c
index f1c8f37541..90537f9a84 100644
--- a/firmware/usb.c
+++ b/firmware/usb.c
@@ -74,7 +74,7 @@ static int usb_mmc_countdown = 0;
 
 /* FIXME: The extra 0x400 is consumed by fat_mount() when the fsinfo
    needs updating */
-static char usb_stack[DEFAULT_STACK_SIZE + 0x400];
+static long usb_stack[(DEFAULT_STACK_SIZE + 0x400)/4];
 static const char usb_thread_name[] = "usb";
 static struct event_queue usb_queue;
 static bool last_usb_status;