diff --git a/pyproject.toml b/pyproject.toml
index e999445..7a9a0c7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -9,7 +9,7 @@ repository = "https://github.com/vale981/hopsflow"
 [tool.poetry.dependencies]
 python = ">=3.9,<3.11"
 sqlitedict = "^1.7.0"
-numpy = "^1.21.4"
+numpy = "^1.20.0"
 scipy = "^1.7.3"
 stocproc = { git = "https://github.com/vale981/stocproc" }
 tqdm = "^4.62.3"