diff --git a/pyproject.toml b/pyproject.toml
index a8af50bfa4c8f8e3041a0937e65fc4eaa91d85a4..91bc70bc0cb2b644d7879a1105d2892b36b0e098 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -21,7 +21,7 @@ texttable = "^1.6"
 PyNaCl = "^1.3"
 
 [tool.poetry.dev-dependencies]
-black = {version = "^19.10b0", allow-prereleases = true, python = "3.6"}
+black = {version = "^19.10b0", allow-prereleases = true, python = "^3.6"}
 pre-commit = "^1.18"
 pytest = "^5.1"
 pytest-cov = "^2.7"