diff --git a/CHANGELOG.md b/CHANGELOG.md
index cd17117b4..d04bef9d0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ customers cannot upgrade their bootloader, its changes are recorded separately.
 - Update manufacturer HID descriptor to bitbox.swiss
 - Ethereum: remove deprecated Goerli network
 - SD card: solve backup bug when sd card is re-inserted
+- SD card: prompt user for formatting if sd is not VFAT compatible
 
 ### 9.21.0
 - Bitcoin: add support for sending to silent payment (BIP-352) addresses
diff --git a/src/rust/bitbox02-rust/src/hww/api/backup.rs b/src/rust/bitbox02-rust/src/hww/api/backup.rs
index c26e50d34..f960aaf8c 100644
--- a/src/rust/bitbox02-rust/src/hww/api/backup.rs
+++ b/src/rust/bitbox02-rust/src/hww/api/backup.rs
@@ -89,6 +89,17 @@ pub async fn create(
     })
     .await?;
 
+    let is_vfat_formatted = bitbox02::sd::sdcard_vfat_formatted();
+    if !is_vfat_formatted {
+        confirm::confirm(&confirm::Params {
+            title: "SD card\nformatting needed",
+            body: "This will erase all\ndata on the SD card.",
+            ..Default::default()
+        })
+        .await?;
+        bitbox02::sd::format()?;
+    }
+
     let is_initialized = bitbox02::memory::is_initialized();
 
     if is_initialized {
diff --git a/src/rust/bitbox02-sys/build.rs b/src/rust/bitbox02-sys/build.rs
index 7bc80b41e..3122ee4fa 100644
--- a/src/rust/bitbox02-sys/build.rs
+++ b/src/rust/bitbox02-sys/build.rs
@@ -117,6 +117,7 @@ const ALLOWLIST_FNS: &[&str] = &[
     "screen_saver_disable",
     "screen_saver_enable",
     "sd_card_inserted",
+    "sd_card_vfat_formatted",
     "sd_erase_file_in_subdir",
     "sd_format",
     "sd_free_list",
diff --git a/src/rust/bitbox02/src/sd.rs b/src/rust/bitbox02/src/sd.rs
index feda371bf..b4c9e3479 100644
--- a/src/rust/bitbox02/src/sd.rs
+++ b/src/rust/bitbox02/src/sd.rs
@@ -30,6 +30,23 @@ pub fn sdcard_inserted() -> bool {
     data.sdcard_inserted.unwrap()
 }
 
+#[cfg(not(feature = "testing"))]
+pub fn sdcard_vfat_formatted() -> bool {
+    unsafe { bitbox02_sys::sd_card_vfat_formatted() }
+}
+
+#[cfg(feature = "testing")]
+pub fn sdcard_vfat_formatted() -> bool {
+    true
+}
+
+pub fn format() -> Result<(), ()> {
+    match unsafe { bitbox02_sys::sd_format() } {
+        true => Ok(()),
+        false => Err(()),
+    }
+}
+
 struct SdList(bitbox02_sys::sd_list_t);
 
 impl Drop for SdList {
diff --git a/src/sd.c b/src/sd.c
index 2b281d27f..7dc5e423e 100644
--- a/src/sd.c
+++ b/src/sd.c
@@ -370,7 +370,14 @@ bool sd_erase_file_in_subdir(const char* fn, const char* subdir)
     return status;
 }
 
-#ifdef TESTING
+bool sd_card_vfat_formatted(void)
+{
+    memset(&fs, 0, sizeof(FATFS));
+    FRESULT res = f_mount(&fs, "", 1);
+    f_unmount("");
+    return res == FR_OK;
+}
+
 bool sd_format(void)
 {
     const MKFS_PARM params = {
@@ -384,4 +391,3 @@ bool sd_format(void)
     uint8_t work[FF_MAX_SS] = {0};
     return f_mkfs("SD", &params, work, sizeof(work)) == FR_OK;
 }
-#endif
diff --git a/src/sd.h b/src/sd.h
index f39d3aeeb..b9fe7dccf 100644
--- a/src/sd.h
+++ b/src/sd.h
@@ -64,8 +64,7 @@ USE_RESULT bool sd_write_bin(
     uint16_t length,
     bool replace);
 
-#ifdef TESTING
+USE_RESULT bool sd_card_vfat_formatted(void);
 USE_RESULT bool sd_format(void);
-#endif
 
 #endif