diff --git a/.cargo/config.toml b/.cargo/config.toml
new file mode 100644
index 00000000..b975a613
--- /dev/null
+++ b/.cargo/config.toml
@@ -0,0 +1,3 @@
+[alias]
+
+fmt-unstable = ["fmt", "--", "--config-path", ".rustfmt.unstable.toml"]
diff --git a/.rustfmt.unstable.toml b/.rustfmt.unstable.toml
new file mode 100644
index 00000000..521dae77
--- /dev/null
+++ b/.rustfmt.unstable.toml
@@ -0,0 +1,6 @@
+# keep in sync with .rustfmt.toml
+chain_width = 40
+
+# format imports
+group_imports = "StdExternalCrate"
+imports_granularity = "Module"