diff --git a/tests/test_regressions.py b/tests/test_regressions.py
new file mode 100644
index 0000000..3932f91
--- /dev/null
+++ b/tests/test_regressions.py
@@ -0,0 +1,5 @@
+import htmlgenerator as hg
+
+
+def test_str_format_zero():
+    assert hg.render(hg.format("1{}", hg.C("value")), {"value": 0}) == "10"