diff --git a/default.nix b/default.nix
index 1a96e22..aa32fc2 100644
--- a/default.nix
+++ b/default.nix
@@ -3,8 +3,8 @@ with pkgs;
 let
   agent_src = fetchgit {
     url = "https://gitea.rixxc.de/rixxc/x25519_agent.git";
-    rev = "b7af39ff804a34bab696cb8ed4ff820e57769aba";
-    hash = "sha256-QUNhUehV0/cfQOQumYRTZvNwBIlgRMz7yN2/wRCNDEE=";
+    rev = "201f270624487ded538b63cc5416456bd5b8ba18";
+    hash = "sha256-KPaKG+t3qSMy4Y7fd0PlBWZiZYcs7M1Clmn75emC9LU=";
   };
 
   agent = callPackage "${agent_src}/default.nix" { };
diff --git a/src/main.rs b/src/main.rs
index 8451ddb..75b37b6 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,5 @@
 use libc::{
-    c_char, c_int, c_void, mmap, perror, MAP_FAILED, MAP_PRIVATE, MAP_SHARED, PROT_READ, PROT_WRITE,
+    c_int, c_void, mmap, MAP_FAILED, MAP_SHARED, PROT_READ, PROT_WRITE,
 };
 use std::fs::File;
 use std::os::fd::AsRawFd;
@@ -9,7 +9,7 @@ const SHARED_MEMORY_SIZE: usize = 1024;
 
 #[link(name = "agent")]
 extern "C" {
-    fn agent_start(shared_memory: *mut u8, sync_memory: *mut u8, private_mem: *mut u8);
+    fn agent_start(shared_memory: *mut u8, sync_memory: *mut u8, private_mem_fd: u64);
 }
 
 fn main() {
@@ -51,21 +51,12 @@ fn main() {
         .read(true)
         .write(true)
         .open(&args[2])
-        .expect("Cannot open KEY_FILE");
-
-    let private_mem = unsafe {
-        mmap(
-            ptr::null_mut() as *mut c_void,
-            32 * 100,
-            PROT_READ | PROT_WRITE,
-            MAP_SHARED,
-            private_file.as_raw_fd(),
-            0,
-        )
-    } as *mut u8;
-    assert_ne!(private_mem, MAP_FAILED as *mut u8);
+        .expect("Cannot open KEY_FILE")
+        .as_raw_fd()
+        .try_into()
+        .unwrap();
 
     unsafe {
-        agent_start(shared_memory, sync_memory, private_mem);
+        agent_start(shared_memory, sync_memory, private_file);
     }
 }