diff --git a/default.nix b/default.nix
index a06bbc6c..885e2dbe 100644
--- a/default.nix
+++ b/default.nix
@@ -14,7 +14,7 @@ let
       version = "0.1.0";
 
       src = ./src;
-      cargoSha256 = "0da6smxhlq1z739g8pdhmkfiq7b8vjqapvskz58rzklh9scf2i99";
+      cargoSha256 = "1lxjb37vl7s359r4801n7b73wnm3p28qlafl04vs9pznadcf6ar0";
 
       nativeBuildInputs = [
         pkgs.gnumake
diff --git a/src/Cargo.lock b/src/Cargo.lock
index 7cedaea3..e97e3c72 100644
--- a/src/Cargo.lock
+++ b/src/Cargo.lock
@@ -201,7 +201,7 @@ dependencies = [
 [[package]]
 name = "libasync"
 version = "0.0.0"
-source = "git+https://git.m-labs.hk/M-Labs/zc706.git#25c6d5eeaa6243724700e975e3935a5965c09a27"
+source = "git+https://git.m-labs.hk/M-Labs/zc706.git#3958953ceb56aa81e33fb4f3d19ab7ee4c06d1ba"
 dependencies = [
  "embedded-hal",
  "libcortex_a9",
@@ -213,7 +213,7 @@ dependencies = [
 [[package]]
 name = "libboard_zynq"
 version = "0.0.0"
-source = "git+https://git.m-labs.hk/M-Labs/zc706.git#25c6d5eeaa6243724700e975e3935a5965c09a27"
+source = "git+https://git.m-labs.hk/M-Labs/zc706.git#3958953ceb56aa81e33fb4f3d19ab7ee4c06d1ba"
 dependencies = [
  "bit_field",
  "embedded-hal",
@@ -237,7 +237,7 @@ dependencies = [
 [[package]]
 name = "libcortex_a9"
 version = "0.0.0"
-source = "git+https://git.m-labs.hk/M-Labs/zc706.git#25c6d5eeaa6243724700e975e3935a5965c09a27"
+source = "git+https://git.m-labs.hk/M-Labs/zc706.git#3958953ceb56aa81e33fb4f3d19ab7ee4c06d1ba"
 dependencies = [
  "bit_field",
  "libregister",
@@ -252,7 +252,7 @@ checksum = "c7d73b3f436185384286bd8098d17ec07c9a7d2388a6599f824d8502b529702a"
 [[package]]
 name = "libregister"
 version = "0.0.0"
-source = "git+https://git.m-labs.hk/M-Labs/zc706.git#25c6d5eeaa6243724700e975e3935a5965c09a27"
+source = "git+https://git.m-labs.hk/M-Labs/zc706.git#3958953ceb56aa81e33fb4f3d19ab7ee4c06d1ba"
 dependencies = [
  "bit_field",
  "vcell",
@@ -262,7 +262,7 @@ dependencies = [
 [[package]]
 name = "libsupport_zynq"
 version = "0.0.0"
-source = "git+https://git.m-labs.hk/M-Labs/zc706.git#25c6d5eeaa6243724700e975e3935a5965c09a27"
+source = "git+https://git.m-labs.hk/M-Labs/zc706.git#3958953ceb56aa81e33fb4f3d19ab7ee4c06d1ba"
 dependencies = [
  "compiler_builtins",
  "libboard_zynq",
diff --git a/src/runtime/src/kernel/control.rs b/src/runtime/src/kernel/control.rs
index 9a7d1a91..91fefa31 100644
--- a/src/runtime/src/kernel/control.rs
+++ b/src/runtime/src/kernel/control.rs
@@ -1,7 +1,7 @@
 use libcortex_a9::sync_channel::{Sender, Receiver};
 use libsupport_zynq::boot::Core1;
 
-use super::{CHANNEL_0TO1, CHANNEL_1TO0, Message};
+use super::{CHANNEL_0TO1, CHANNEL_1TO0, INIT_LOCK, Message};
 use crate::irq::restart_core1;
 
 use core::mem::{forget, replace};
@@ -39,7 +39,13 @@ impl Control {
     }
 
     pub fn restart(&mut self) {
-        restart_core1();
+        {
+            INIT_LOCK.lock();
+            restart_core1();
+            unsafe {
+                self.tx.drop_elements();
+            }
+        }
         let (core0_tx, core0_rx) = get_channels();
         // dangling pointer here, so we forget it
         forget(replace(&mut self.tx, core0_tx));
diff --git a/src/runtime/src/kernel/core1.rs b/src/runtime/src/kernel/core1.rs
index ac0632bf..15cf156b 100644
--- a/src/runtime/src/kernel/core1.rs
+++ b/src/runtime/src/kernel/core1.rs
@@ -18,6 +18,7 @@ use crate::eh_artiq;
 use super::{
     api::resolve,
     rpc::rpc_send_async,
+    INIT_LOCK,
     CHANNEL_0TO1, CHANNEL_1TO0,
     KERNEL_CHANNEL_0TO1, KERNEL_CHANNEL_1TO0,
     KERNEL_IMAGE,
@@ -147,6 +148,7 @@ pub fn main_core1() {
     let (mut core0_tx, mut core1_rx) = sync_channel!(Message, 4);
     let (mut core1_tx, core0_rx) = sync_channel!(Message, 4);
     unsafe {
+        INIT_LOCK.lock();
         core0_tx.reset();
         core1_tx.reset();
         dma::init_dma_recorder();
diff --git a/src/runtime/src/kernel/mod.rs b/src/runtime/src/kernel/mod.rs
index 6605fce3..ea3ecd54 100644
--- a/src/runtime/src/kernel/mod.rs
+++ b/src/runtime/src/kernel/mod.rs
@@ -54,3 +54,5 @@ static KERNEL_CHANNEL_1TO0: Mutex<Option<sync_channel::Sender<'static, Message>>
 
 static mut KERNEL_IMAGE: *const core1::KernelImage = ptr::null();
 
+static INIT_LOCK: Mutex<()> = Mutex::new(());
+