diff --git a/assemblers/org.osbuild.qemu b/assemblers/org.osbuild.qemu
index 7fbe8451..201d96fd 100755
--- a/assemblers/org.osbuild.qemu
+++ b/assemblers/org.osbuild.qemu
@@ -98,7 +98,13 @@ def main(tree, output_dir, options, loop_client):
         mount(loop, mountpoint):
         subprocess.run(["cp", "-a", f"{tree}/.", mountpoint], check=True)
 
-    subprocess.run(["qemu-img", "convert", "-O", fmt, "-c", image, f"{output_dir}/{filename}"], check=True)
+    extra_args = []
+
+    # raw and vdi don't suppport compression
+    if fmt != "raw" and fmt != "vdi":
+        extra_args.append("-c")
+
+    subprocess.run(["qemu-img", "convert", "-O", fmt, *extra_args, image, f"{output_dir}/{filename}"], check=True)
 
 if __name__ == '__main__':
     args = json.load(sys.stdin)