diff --git a/scripts/build.sh b/scripts/build.sh
index d24663a..6d31c3d 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -730,7 +730,7 @@ sign_manifest() {
 }
 
 build_manifest() {
-	python3 scripts/build_manifest.py "$UPDATE_DIR" "$CHROOT_BASEDIR" "$VERSION"
+	python3 scripts/build_manifest.py "$UPDATE_DIR" "$CHROOT_BASEDIR"
 }
 
 build_update_image() {
diff --git a/scripts/build_manifest.py b/scripts/build_manifest.py
index 8e12f60..29079b9 100644
--- a/scripts/build_manifest.py
+++ b/scripts/build_manifest.py
@@ -8,7 +8,10 @@ import subprocess
 import sys
 
 if __name__ == "__main__":
-    output, rootfs, version = sys.argv[1:]
+    output, rootfs = sys.argv[1:]
+
+    with open(os.path.join(rootfs, "etc/version")) as f:
+        version = f.read().strip()
 
     size = int(int(subprocess.run(
         ["du", "--block-size", "1", "-d", "0", "-x", rootfs],