diff --git a/pyproject.toml b/pyproject.toml
index d12e33df9..e70fa244c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -5,7 +5,7 @@ build-backend = "maturin"
 [project]
 name = "ffsim"
 requires-python = ">=3.9"
-version = "0.0.38"
+version = "0.0.39.dev"
 description = "Faster simulations of fermionic quantum circuits."
 readme = "README.md"
 license = { file = "LICENSE" }