diff --git a/resize/resize.ml b/resize/resize.ml
index d15f070751..675a6e1c45 100644
--- a/resize/resize.ml
+++ b/resize/resize.ml
@@ -98,7 +98,7 @@ let infile, outfile, align_first, alignment, copy_boot_loader,
     "--dryrun",  Arg.Set dryrun,            " -\"-";
     "--dry-run", Arg.Set dryrun,            " -\"-";
     "--ntfsresize-force", Arg.Set ntfsresize_force, " Force ntfsresize";
-    "--output-format", Arg.Set_string format, "format Format of output disk";
+    "--output-format", Arg.Set_string output_format, "format Format of output disk";
     "-q",        Arg.Set quiet,             " Don't print the summary";
     "--quiet",   Arg.Set quiet,             " -\"-";
     "--resize",  Arg.String (add resizes),  "part=size Resize partition";
diff --git a/resize/test-virt-resize.sh b/resize/test-virt-resize.sh
index 7e38a439f2..984232702b 100755
--- a/resize/test-virt-resize.sh
+++ b/resize/test-virt-resize.sh
@@ -27,7 +27,11 @@ set -e
 ../fish/guestfish -N bootrootlv:/dev/VG/LV:ext2:ext4:400M:32M:gpt </dev/null
 
 qemu-img create -f qcow2 test2.img 500M
-$VG ./virt-resize -d --debug-gc --expand /dev/sda2 --lv-expand /dev/VG/LV test1.img test2.img
+$VG ./virt-resize -d --debug-gc \
+    --expand /dev/sda2 \
+    --lv-expand /dev/VG/LV \
+    --format raw --output-format qcow2 \
+    test1.img test2.img
 
 # Test shrinking in a semi-realistic scenario.  Although the disk
 # image created above contains no data, we will nevertheless use
@@ -42,6 +46,9 @@ fsck ext4 /dev/VG/LV
 EOF
 
 rm -f test2.img; truncate -s 300M test2.img
-$VG ./virt-resize -d --debug-gc --shrink /dev/sda2 test1.img test2.img
+$VG ./virt-resize -d --debug-gc \
+    --shrink /dev/sda2 \
+    --format raw --output-format raw \
+    test1.img test2.img
 
 rm -f test1.img test2.img