diff --git a/CHANGELOG.md b/CHANGELOG.md
index cd03ac35..744082ad 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,10 @@ change warranting a new major release:
 
 eive-tmtc: v2.12.3
 
+## Fixed
+
+- `SdCardManager.cpp` `isSdCardUsable`: Use `ext4` instead of `vfat` to check read-only state.
+
 # [v1.26.3] 2023-02-09
 
 eive-tmtc: v2.12.2
diff --git a/bsp_q7s/fs/SdCardManager.cpp b/bsp_q7s/fs/SdCardManager.cpp
index 9d5fcd6e..c0b1184e 100644
--- a/bsp_q7s/fs/SdCardManager.cpp
+++ b/bsp_q7s/fs/SdCardManager.cpp
@@ -505,9 +505,9 @@ bool SdCardManager::isSdCardUsable(std::optional<sd::SdCard> sdCard) {
 ReturnValue_t SdCardManager::isSdCardMountedReadOnly(sd::SdCard sdcard, bool& readOnly) {
   std::ostringstream command;
   if (sdcard == sd::SdCard::SLOT_0) {
-    command << "grep -q '" << config::SD_0_MOUNT_POINT << " vfat ro,' /proc/mounts";
+    command << "grep -q '" << config::SD_0_MOUNT_POINT << " ext4 ro,' /proc/mounts";
   } else if (sdcard == sd::SdCard::SLOT_1) {
-    command << "grep -q '" << config::SD_1_MOUNT_POINT << " vfat ro,' /proc/mounts";
+    command << "grep -q '" << config::SD_1_MOUNT_POINT << " ext4 ro,' /proc/mounts";
   } else {
     return returnvalue::FAILED;
   }