diff --git a/pyproject.toml b/pyproject.toml
index 34cd0f9..0e90210 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -21,7 +21,7 @@ fits = ["fitsio"]
 
 [tool.poetry.group.dev.dependencies]
 pytest = "^8.0.0"
-coveralls = "^3.3.1"
+coveralls = "^4.0.0"
 mypy = "^1.0.1"
 
 [build-system]