diff --git a/devtools/flake.lock b/devtools/flake.lock
index 4d880925a3c..11b30cd5d98 100644
--- a/devtools/flake.lock
+++ b/devtools/flake.lock
@@ -101,8 +101,8 @@
         "rust-overlay": "rust-overlay"
       },
       "locked": {
-        "lastModified": 1712750088,
-        "narHash": "sha256-qao1J0xx+eCuCdOTCf4wPkkKmwHdJy1uof4QKhO/yOc=",
+        "lastModified": 1722362288,
+        "narHash": "sha256-tjwYO8AH2Skwhynm/fwOTodN/EqLgAbvKzhE/xxQ2r8=",
         "path": "/home/username/gitrepos/roc",
         "type": "path"
       },
@@ -129,11 +129,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1712369449,
-        "narHash": "sha256-tbWug3uXPlSm1j0xD80Y3xbP+otT6gLnQo1e/vQat48=",
+        "lastModified": 1713150335,
+        "narHash": "sha256-Ic7zCPfiSYc9nFFp+E44WFk3TBJ99J/uPZ4QXX+uPPw=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "41b3b080cc3e4b3a48e933b87fc15a05f1870779",
+        "rev": "b186d85e747e2b7bee220ec95839fb66c868dc47",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index b8e952c3f95..8487f2bd822 100644
--- a/flake.nix
+++ b/flake.nix
@@ -150,7 +150,10 @@
           full = rocBuild.roc-full;
           # only the CLI crate = executable provided in nightly releases
           cli = rocBuild.roc-cli;
+          cli-debug = rocBuild.roc-cli-debug;
+
           lang-server = rocBuild.roc-lang-server;
+          lang-server-debug = rocBuild.roc-lang-server-debug;
         };
 
         apps = {
diff --git a/nix/builder.nix b/nix/builder.nix
index 31fc1df6821..48782e54c5a 100644
--- a/nix/builder.nix
+++ b/nix/builder.nix
@@ -5,92 +5,98 @@ let
   subPackagePath = if subPackage != null then "crates/${subPackage}" else null;
   mainBin = if subPackage == "language_server" then "roc_language_server" else "roc";
   filteredSource = pkgs.callPackage ./fileFilter.nix { };
-in
-rustPlatform.buildRustPackage {
-  pname = "roc" + lib.optionalString (subPackage != null) "_${subPackage}";
-  version = "0.0.1";
+  buildRoc = buildTypeStr:
+    rustPlatform.buildRustPackage {
+      pname = "roc" + lib.optionalString (subPackage != null) "_${subPackage}";
+      version = "0.0.1";
+      buildType = buildTypeStr;
 
-  buildAndTestSubdir = subPackagePath;
+      buildAndTestSubdir = subPackagePath;
 
-  src = filteredSource;
+      src = filteredSource;
 
-  cargoLock = {
-    lockFile = ../Cargo.lock;
-    outputHashes = {
-      "criterion-0.3.5" = "sha256-+FibPQGiR45g28xCHcM0pMN+C+Q8gO8206Wb5fiTy+k=";
-      "inkwell-0.2.0" = "sha256-VhTapYGonoSQ4hnDoLl4AAgj0BppAhPNA+UPuAJSuAU=";
-      "plotters-0.3.1" = "sha256-noy/RSjoEPZZbOJTZw1yxGcX5S+2q/7mxnUrzDyxOFw=";
-      "rustyline-9.1.1" = "sha256-aqQqz6nSp+Qn44gm3jXmmQUO6/fYTx7iLph2tbA24Bs=";
-    };
-  };
+      cargoLock = {
+        lockFile = ../Cargo.lock;
+        outputHashes = {
+          "criterion-0.3.5" = "sha256-+FibPQGiR45g28xCHcM0pMN+C+Q8gO8206Wb5fiTy+k=";
+          "inkwell-0.2.0" = "sha256-VhTapYGonoSQ4hnDoLl4AAgj0BppAhPNA+UPuAJSuAU=";
+          "plotters-0.3.1" = "sha256-noy/RSjoEPZZbOJTZw1yxGcX5S+2q/7mxnUrzDyxOFw=";
+          "rustyline-9.1.1" = "sha256-aqQqz6nSp+Qn44gm3jXmmQUO6/fYTx7iLph2tbA24Bs=";
+        };
+      };
 
-  shellHook = ''
-    export LLVM_SYS_${llvmMajorMinorStr}_PREFIX="${llvmPkgs.llvm.dev}"
-  '';
+      shellHook = ''
+        export LLVM_SYS_${llvmMajorMinorStr}_PREFIX="${llvmPkgs.llvm.dev}"
+      '';
 
-  # required for zig
-  XDG_CACHE_HOME =
-    "xdg_cache"; # prevents zig AccessDenied error github.com/ziglang/zig/issues/6810
-  # want to see backtrace in case of failure
-  RUST_BACKTRACE = 1;
+      # required for zig
+      XDG_CACHE_HOME =
+        "xdg_cache"; # prevents zig AccessDenied error github.com/ziglang/zig/issues/6810
+      # want to see backtrace in case of failure
+      RUST_BACKTRACE = 1;
 
-  # skip running rust tests, problems:
-  # building of example platforms requires network: Could not resolve host
-  # zig AccessDenied error github.com/ziglang/zig/issues/6810
-  # Once instance has previously been poisoned ??
-  doCheck = false;
+      # skip running rust tests, problems:
+      # building of example platforms requires network: Could not resolve host
+      # zig AccessDenied error github.com/ziglang/zig/issues/6810
+      # Once instance has previously been poisoned ??
+      doCheck = false;
 
-  nativeBuildInputs = (with pkgs; [
-    cmake
-    git
-    pkg-config
-    python3
-    llvmPkgs.clang
-    llvmPkgs.llvm.dev
-    llvmPkgs.bintools-unwrapped # contains lld
-    zigPkg
-  ]);
+      nativeBuildInputs = (with pkgs; [
+        cmake
+        git
+        pkg-config
+        python3
+        llvmPkgs.clang
+        llvmPkgs.llvm.dev
+        llvmPkgs.bintools-unwrapped # contains lld
+        zigPkg
+      ]);
 
-  buildInputs = (with pkgs;
-    [
-      libffi
-      libxml2
-      ncurses
-      zlib
-      cargo
-      makeWrapper # necessary for postBuild wrapProgram
-    ] ++ lib.optionals pkgs.stdenv.isDarwin
-      (with pkgs.darwin.apple_sdk.frameworks;
-      [
-        AppKit
-        CoreFoundation
-        CoreServices
-        Foundation
-        Security
-      ]));
+      buildInputs = (with pkgs;
+        [
+          libffi
+          libxml2
+          ncurses
+          zlib
+          cargo
+          makeWrapper # necessary for postBuild wrapProgram
+        ] ++ lib.optionals pkgs.stdenv.isDarwin
+          (with pkgs.darwin.apple_sdk.frameworks;
+          [
+            AppKit
+            CoreFoundation
+            CoreServices
+            Foundation
+            Security
+          ]));
 
-  # cp: to copy str.zig,list.zig...
-  # wrapProgram pkgs.stdenv.cc: to make ld available for compiler/build/src/link.rs
-  postInstall =
-    let
-      binPath =
-        lib.makeBinPath [ pkgs.stdenv.cc ];
-      linuxArgs = lib.optionalString pkgs.stdenv.isLinux
-        "--set NIX_GLIBC_PATH ${glibcPath} --set NIX_LIBGCC_S_PATH ${libGccSPath}";
-      rocPath = "$out/bin/roc";
-      wrapRoc = "wrapProgram ${rocPath} ${linuxArgs} --prefix PATH : ${binPath}";
-    in
-    # need to check if roc bin exists since it might not if subPackage is set
-    ''
-      if test -f ${rocPath}; then
-        ${wrapRoc}
-      fi
-    '';
+      # cp: to copy str.zig,list.zig...
+      # wrapProgram pkgs.stdenv.cc: to make ld available for compiler/build/src/link.rs
+      postInstall =
+        let
+          binPath =
+            lib.makeBinPath [ pkgs.stdenv.cc ];
+          linuxArgs = lib.optionalString pkgs.stdenv.isLinux
+            "--set NIX_GLIBC_PATH ${glibcPath} --set NIX_LIBGCC_S_PATH ${libGccSPath}";
+          rocPath = "$out/bin/roc";
+          wrapRoc = "wrapProgram ${rocPath} ${linuxArgs} --prefix PATH : ${binPath}";
+        in
+        # need to check if roc bin exists since it might not if subPackage is set
+        ''
+          if test -f ${rocPath}; then
+            ${wrapRoc}
+          fi
+        '';
 
-  # https://ryantm.github.io/nixpkgs/stdenv/meta/
-  meta = {
-    homepage = "https://www.roc-lang.org/";
-    license = lib.licenses.upl;
-    mainProgram = mainBin;
-  };
+      # https://ryantm.github.io/nixpkgs/stdenv/meta/
+      meta = {
+        homepage = "https://www.roc-lang.org/";
+        license = lib.licenses.upl;
+        mainProgram = mainBin;
+      };
+    };
+in
+{
+  roc-debug = buildRoc "debug";
+  roc-release = buildRoc "release";
 }
diff --git a/nix/default.nix b/nix/default.nix
index 8a9e167816b..e54aa8a2acf 100644
--- a/nix/default.nix
+++ b/nix/default.nix
@@ -16,11 +16,16 @@ let
     rust-shell =
       (rustVersion.override { extensions = [ "rust-src" "rust-analyzer" ]; });
 
-    # all rust crates in workspace.members of Cargo.toml
-    roc-full = callPackage ./builder.nix { };
-    roc-lang-server = callPackage ./builder.nix { subPackage = "language_server"; };
+    # contains all rust crates in workspace.members of Cargo.toml
+    roc-full = (callPackage ./builder.nix { }).roc-release;
+    roc-full-debug = (callPackage ./builder.nix { }).roc-debug;
+
+    roc-lang-server = (callPackage ./builder.nix { subPackage = "language_server"; }).roc-release;
+    roc-lang-server-debug = (callPackage ./builder.nix { subPackage = "language_server"; }).roc-debug;
+
     # only the CLI crate = executable provided in nightly releases
-    roc-cli = callPackage ./builder.nix { subPackage = "cli"; };
+    roc-cli = (callPackage ./builder.nix { subPackage = "cli"; }).roc-release;
+    roc-cli-debug = (callPackage ./builder.nix { subPackage = "cli"; }).roc-debug;
   };
 
 in
diff --git a/nix/fileFilter.nix b/nix/fileFilter.nix
index 8f974f85b21..a8c0fb7cab5 100644
--- a/nix/fileFilter.nix
+++ b/nix/fileFilter.nix
@@ -37,6 +37,8 @@ let
     ../Cargo.toml
     ../Cargo.lock
     ../version.txt
+    ../rust-toolchain.toml
+    ../.cargo/config.toml
     onlyCratesFolder
   ];