diff --git a/.gitignore b/.gitignore
index 4169afcd..79866888 100644
--- a/.gitignore
+++ b/.gitignore
@@ -25,3 +25,6 @@ rusty-tags.*
 # Python egg metadata, regenerated from source files by setuptools.
 /scripts/*.egg-info
 /scripts/*.egg
+
+# The target directory from Rust development
+/target/
diff --git a/sim/Cargo.lock b/Cargo.lock
similarity index 100%
rename from sim/Cargo.lock
rename to Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 00000000..46b8a672
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,13 @@
+[workspace]
+members = ["sim"]
+exclude = ["ptest"]
+
+# The simulator runs very slowly without optimization.  A value of 1
+# compiles in about half the time, but runs about 5-6 times slower.  2
+# and 3 are hardly different in either compile time or performance.
+# Use 2 in case that makes the code slightly more debuggable.
+[profile.test]
+opt-level = 2
+
+[profile.dev]
+opt-level = 2
diff --git a/sim/Cargo.toml b/sim/Cargo.toml
index 3c47324c..5d5555ea 100644
--- a/sim/Cargo.toml
+++ b/sim/Cargo.toml
@@ -49,13 +49,3 @@ cipher = "0.3"
 aes = { version = "0.7.4", features = ["ctr"] }
 base64 = "0.13.0"
 typenum = "1.13.0"
-
-# The simulator runs very slowly without optimization.  A value of 1
-# compiles in about half the time, but runs about 5-6 times slower.  2
-# and 3 are hardly different in either compile time or performance.
-# Use 2 in case that makes the code slightly more debuggable.
-[profile.test]
-opt-level = 2
-
-[profile.dev]
-opt-level = 2