diff --git a/fish-rust/src/env.rs b/fish-rust/src/env.rs
new file mode 100644
index 000000000..5b88741fb
--- /dev/null
+++ b/fish-rust/src/env.rs
@@ -0,0 +1,37 @@
+/// Flags that may be passed as the 'mode' in env_stack_t::set() / environment_t::get().
+pub mod flags {
+    use autocxx::c_int;
+
+    /// Default mode. Used with `env_stack_t::get()` to indicate the caller doesn't care what scope
+    /// the var is in or whether it is exported or unexported.
+    pub const ENV_DEFAULT: c_int = c_int(0);
+    /// Flag for local (to the current block) variable.
+    pub const ENV_LOCAL: c_int = c_int(1 << 0);
+    pub const ENV_FUNCTION: c_int = c_int(1 << 1);
+    /// Flag for global variable.
+    pub const ENV_GLOBAL: c_int = c_int(1 << 2);
+    /// Flag for universal variable.
+    pub const ENV_UNIVERSAL: c_int = c_int(1 << 3);
+    /// Flag for exported (to commands) variable.
+    pub const ENV_EXPORT: c_int = c_int(1 << 4);
+    /// Flag for unexported variable.
+    pub const ENV_UNEXPORT: c_int = c_int(1 << 5);
+    /// Flag to mark a variable as a path variable.
+    pub const ENV_PATHVAR: c_int = c_int(1 << 6);
+    /// Flag to unmark a variable as a path variable.
+    pub const ENV_UNPATHVAR: c_int = c_int(1 << 7);
+    /// Flag for variable update request from the user. All variable changes that are made directly
+    /// by the user, such as those from the `read` and `set` builtin must have this flag set. It
+    /// serves one purpose: to indicate that an error should be returned if the user is attempting
+    /// to modify a var that should not be modified by direct user action; e.g., a read-only var.
+    pub const ENV_USER: c_int = c_int(1 << 8);
+}
+
+/// Return values for `env_stack_t::set()`.
+pub mod status {
+    pub const ENV_OK: i32 = 0;
+    pub const ENV_PERM: i32 = 1;
+    pub const ENV_SCOPE: i32 = 2;
+    pub const ENV_INVALID: i32 = 3;
+    pub const ENV_NOT_FOUND: i32 = 4;
+}