diff --git a/sphinx_d2lang/d2lang.py b/sphinx_d2lang/d2lang.py
index 78f1dae..ac3e75b 100644
--- a/sphinx_d2lang/d2lang.py
+++ b/sphinx_d2lang/d2lang.py
@@ -18,6 +18,7 @@ class D2langDirective(Directive):
         with tempfile.NamedTemporaryFile() as fp:
             for line in self.content.splitlines():
                 fp.write(bytes(line,'utf-8'))
+                fp.write(bytes('\n','utf-8'))
             fp.seek(0)
             cmd_line = '%s %s %s' % (d2_bin, fp.name, srcdir + "/test.svg")
             args = shlex.split(cmd_line)