diff --git a/pyproject.toml b/pyproject.toml
index dab8b608..481d04c8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,7 +17,7 @@ include = [
 
 [tool.poetry.dependencies]
 python = "^3.11"
-astropy = "*"
+astropy = "6.1.3"
 numpy = "^1.26.0"
 python-casacore = "3.5.2" # newer version caused MS errors (maybe related to pre-built wheel)
 pydantic = "2.8.2" # version 2.9.0 caused prefect model validation error