diff --git a/.gitea/workflows/build.yaml b/.gitea/workflows/build.yaml
index 43f51ef..bdc3b3a 100644
--- a/.gitea/workflows/build.yaml
+++ b/.gitea/workflows/build.yaml
@@ -18,3 +18,8 @@ jobs:
         with:
           name: firmware-RPi-Pico-W
           path: software/lib/micropython/ports/rp2/build-TONBERRY_RPI_PICO_W/firmware.uf2
+      - name: Upload firmware w/ filesystem
+        uses: actions/upload-artifact@v3
+        with:
+          name: firmware-RPi-Pico-W-with-fs
+          path: software/lib/micropython/ports/rp2/build-TONBERRY_RPI_PICO_W/firmware-filesystem.uf2
diff --git a/.gitmodules b/.gitmodules
index 9254853..ddd1dfe 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -7,3 +7,6 @@
 [submodule "software/lib/microdot"]
 	path = software/lib/microdot
 	url = ../microdot.git
+[submodule "software/tools/mklittlefs"]
+	path = software/tools/mklittlefs
+	url = https://github.com/earlephilhower/mklittlefs.git
diff --git a/software/build.sh b/software/build.sh
index a0476a7..30b1429 100755
--- a/software/build.sh
+++ b/software/build.sh
@@ -11,4 +11,25 @@ set -eu
        USER_C_MODULES="$TOPDIR"/src/micropython.cmake -j "$(nproc)"
 )
 
-echo "Output in lib/micropython/ports/rp2/build-TONBERRY_RPI_PICO_W/firmware.uf2"
+( cd tools/mklittlefs
+  make -j "$(nproc)"
+)
+
+PICOTOOL=picotool
+if ! command -v $PICOTOOL >/dev/null 2>&1; then
+    echo "system picotool not found, checking SDK build dir"
+    PICOTOOL=lib/micropython/ports/rp2/build-TONBERRY_RPI_PICO_W/_deps/picotool-build/picotool
+    if ! command -v $PICOTOOL >/dev/null 2>&1; then
+       echo "No picotool found, exiting"
+       exit 1
+    fi
+fi
+BUILDDIR=lib/micropython/ports/rp2/build-TONBERRY_RPI_PICO_W/
+tools/mklittlefs/mklittlefs -p 256 -s 868352 -c src/ $BUILDDIR/filesystem.bin
+truncate -s 2M $BUILDDIR/firmware-filesystem.bin
+dd if=$BUILDDIR/firmware.bin of=$BUILDDIR/firmware-filesystem.bin bs=1k
+dd if=$BUILDDIR/filesystem.bin of=$BUILDDIR/firmware-filesystem.bin bs=1k seek=1200
+$PICOTOOL uf2 convert $BUILDDIR/firmware-filesystem.bin $BUILDDIR/firmware-filesystem.uf2
+
+echo "Output in $BUILDDIR/firmware.uf2"
+echo "Image with filesystem in $BUILDDIR/firmware-filesystem.uf2"
diff --git a/software/tools/mklittlefs b/software/tools/mklittlefs
new file mode 160000
index 0000000..db0513a
--- /dev/null
+++ b/software/tools/mklittlefs
@@ -0,0 +1 @@
+Subproject commit db0513ade5d4ffb757b0529ce277d0be93e4e46a
diff --git a/software/update-submodules.sh b/software/update-submodules.sh
index e494519..a528ef8 100755
--- a/software/update-submodules.sh
+++ b/software/update-submodules.sh
@@ -5,3 +5,4 @@ set -eu
 git submodule update --init lib
 git -C lib/micropython submodule update --init lib/pico-sdk lib/mbedtls lib/micropython-lib lib/tinyusb lib/btstack lib/cyw43-driver lib/lwip
 git -C lib/micropython/lib/pico-sdk submodule update --init lib
+git submodule update --init --recursive tools/mklittlefs