diff --git a/flash b/flash
index e926056..788b468 100755
--- a/flash
+++ b/flash
@@ -573,7 +573,7 @@ if [[ -z $CONFIGURE_ONLY ]] ; then
       echo "Use ${image}"
     fi
 
-    if [[ "$(file "${image}")" == *"xz compressed data"* ]]; then
+    if [[ "$(file "${image}" | tr '[:upper:]' '[:lower:]' )" == *"xz compressed data"* ]]; then
       command -v xz 2>/dev/null || error "Error: unzip not found. Aborting" 1
       echo "Uncompressing ${image} ..."
       xz -d "${image}" -c >/tmp/image.img