diff --git a/Cargo.lock b/Cargo.lock
index f3e1e0d..2711905 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -39,8 +39,7 @@ checksum = "3748f82c7d366a0b4950257d19db685d4958d2fa27c6d164a3f069fec42b748b"
 [[package]]
 name = "core_io"
 version = "0.1.20210325"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "97f8932064288cc79feb4d343a399d353a6f6f001e586ece47fe518a9e8507df"
+source = "git+https://git.m-labs.hk/abdul124/rust-core_io?rev=8005787#80057878c9116fec8aede2e4a121b1182c239eb6"
 dependencies = [
  "rustc_version",
 ]
diff --git a/flake.nix b/flake.nix
index d5b7144..e270ea2 100644
--- a/flake.nix
+++ b/flake.nix
@@ -114,7 +114,12 @@
         src = builtins.filterSource (path: type:
           baseNameOf path != "target"
         ) ./.;
-        cargoLock = { lockFile = ./Cargo.lock; };
+        cargoLock = { 
+          lockFile = src/Cargo.lock;
+          outputHashes = {
+              "core_io-0.1.20210325" = "sha256-2ZdKk+cgsh/WKPlWpCq9A/m+gHxN19Eqix/Om1IwaGM=";
+            };
+        };
 
         nativeBuildInputs = [ cargo-xbuild llvmPackages_11.clang-unwrapped ];
         buildPhase = ''
diff --git a/libconfig/Cargo.toml b/libconfig/Cargo.toml
index 43ea995..8b454fe 100644
--- a/libconfig/Cargo.toml
+++ b/libconfig/Cargo.toml
@@ -6,7 +6,7 @@ edition = "2018"
 
 [dependencies]
 libboard_zynq = { path = "../libboard_zynq" }
-core_io = { version = "0.1", features = ["collections"] }
+core_io = { git = "https://git.m-labs.hk/abdul124/rust-core_io.git", rev = "8005787", features = ["collections"] }
 fatfs = { version = "0.3", features = ["core_io"], default-features = false }
 log = "0.4"
 
diff --git a/szl/Cargo.toml b/szl/Cargo.toml
index b1a33ae..2df6f4c 100644
--- a/szl/Cargo.toml
+++ b/szl/Cargo.toml
@@ -15,7 +15,7 @@ default = ["target_zc706"]
 [dependencies]
 log = "0.4"
 byteorder = { version = "1.3", default-features = false }
-core_io = { version = "0.1", features = ["collections"] }
+core_io = { git = "https://git.m-labs.hk/abdul124/rust-core_io.git", rev = "8005787", features = ["collections"] }
 
 libboard_zynq = { path = "../libboard_zynq" }
 libsupport_zynq = { path = "../libsupport_zynq" }