diff --git a/lib/img-functions b/lib/img-functions
index 8a0ad7bb..f0914840 100644
--- a/lib/img-functions
+++ b/lib/img-functions
@@ -166,7 +166,8 @@ function finalise_base () {
 
 function compress_image () {
     # Recreate our image to throw away unnecessary data
-    qemu-img convert ${COMPRESS_IMAGE:+-c} $TMP_IMAGE_PATH -O qcow2 $TMP_IMAGE_PATH-new
+    test $IMAGE_TYPE != qcow2 && COMPRESS_IMAGE=""
+    qemu-img convert ${COMPRESS_IMAGE:+-c} $TMP_IMAGE_PATH -O $IMAGE_TYPE $TMP_IMAGE_PATH-new
     rm $TMP_IMAGE_PATH
     mv $TMP_IMAGE_PATH-new $TMP_IMAGE_PATH
 }