diff --git a/devtools/debug_tips.md b/devtools/debug_tips.md
index 324ddd00df3..272486b4761 100644
--- a/devtools/debug_tips.md
+++ b/devtools/debug_tips.md
@@ -48,3 +48,23 @@ Note that the addresses shown in objdump may use a different offset compared to
 
 gdb scripting is very useful, [for example](https://roc.zulipchat.com/#narrow/stream/395097-compiler-development/topic/gdb.20script/near/424422545).
 ChatGPT and Claude are good at writing those scripts as well.
+
+## Code Coverage
+
+When investigating a bug, it can be nice to instantly see if a line of rust code was executed during for example `roc build yourFile.roc`. We can use [`cargo-llvm-cov`](https://github.com/taiki-e/cargo-llvm-cov) for this, on linux, it comes pre-installed with our flake.nix. On macos you'll need to install it with `cargo +stable install cargo-llvm-cov --locked`.
+
+To generate the code coverage file:
+
+```shell
+$ cd roc
+$ source <(cargo llvm-cov show-env --export-prefix)
+$ cargo llvm-cov clean --workspace
+$ cargo build --bin roc
+# Replace with the command you want to generate coverage for:
+$ ./target/debug/roc build ./examples/platform-switching/rocLovesRust.roc
+# To view in editor
+$ cargo llvm-cov report --lcov  --output-path lcov.info
+# To view in browser
+$ cargo llvm-cov report --html
+```
+Viewing lcov.info will depend on your editor. For vscode, you can use the [coverage gutters](https://marketplace.visualstudio.com/items?itemName=ryanluker.vscode-coverage-gutters) extension. After installing, click `Watch` in the bottom bar and go to a file for which you want to see the coverage, for example `crates/compiler/build/src/link.rs`. `Watch` in the bottom bar will now be replaced with `x% Coverage`.
diff --git a/devtools/flake.lock b/devtools/flake.lock
index 11b30cd5d98..eee0bba6c29 100644
--- a/devtools/flake.lock
+++ b/devtools/flake.lock
@@ -21,11 +21,11 @@
         "systems": "systems"
       },
       "locked": {
-        "lastModified": 1710146030,
-        "narHash": "sha256-SZ5L6eA7HJ/nmkzGG7/ISclqe6oZdOZTNoesiInkXPQ=",
+        "lastModified": 1726560853,
+        "narHash": "sha256-X6rJYSESBVr3hBoH0WbKE5KvhPU5bloyZ2L4K60/fPQ=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "b1d9ab70662946ef0850d488da1c9019f3a9752a",
+        "rev": "c1dfcf08411b08f6b8615f7d8971a2bfa81d5e8a",
         "type": "github"
       },
       "original": {
@@ -101,8 +101,8 @@
         "rust-overlay": "rust-overlay"
       },
       "locked": {
-        "lastModified": 1722362288,
-        "narHash": "sha256-tjwYO8AH2Skwhynm/fwOTodN/EqLgAbvKzhE/xxQ2r8=",
+        "lastModified": 1727455099,
+        "narHash": "sha256-/tqXI2VIsx+OmXxYAUqOnzfQ2JqWBJJ32IjwzGMxg0A=",
         "path": "/home/username/gitrepos/roc",
         "type": "path"
       },
@@ -175,4 +175,4 @@
   },
   "root": "root",
   "version": 7
-}
+}
\ No newline at end of file
diff --git a/devtools/flake.nix b/devtools/flake.nix
index 228feadd6fa..992d07592e4 100755
--- a/devtools/flake.nix
+++ b/devtools/flake.nix
@@ -32,7 +32,7 @@
               vscodeWithExtensions = pkgs.vscode-with-extensions.override {
                 vscodeExtensions = with pkgs.vscode-extensions;
                   [
-                    matklad.rust-analyzer
+                    rust-lang.rust-analyzer
                     # eamodio.gitlens
                     bbenoist.nix
                     tamasfe.even-better-toml
diff --git a/flake.lock b/flake.lock
index 511c9adf186..dbaac0648a6 100644
--- a/flake.lock
+++ b/flake.lock
@@ -21,11 +21,11 @@
         "systems": "systems"
       },
       "locked": {
-        "lastModified": 1710146030,
-        "narHash": "sha256-SZ5L6eA7HJ/nmkzGG7/ISclqe6oZdOZTNoesiInkXPQ=",
+        "lastModified": 1726560853,
+        "narHash": "sha256-X6rJYSESBVr3hBoH0WbKE5KvhPU5bloyZ2L4K60/fPQ=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "b1d9ab70662946ef0850d488da1c9019f3a9752a",
+        "rev": "c1dfcf08411b08f6b8615f7d8971a2bfa81d5e8a",
         "type": "github"
       },
       "original": {
@@ -44,11 +44,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1710868679,
-        "narHash": "sha256-V1o2bCZdeYKP/0zgVp4EN0KUjMItAMk6J7SvCXUI5IU=",
+        "lastModified": 1713543440,
+        "narHash": "sha256-lnzZQYG0+EXl/6NkGpyIz+FEOc/DSEG57AP1VsdeNrM=",
         "owner": "guibou",
         "repo": "nixGL",
-        "rev": "d709a8abcde5b01db76ca794280745a43c8662be",
+        "rev": "310f8e49a149e4c9ea52f1adf70cdc768ec53f8a",
         "type": "github"
       },
       "original": {
@@ -84,19 +84,16 @@
     },
     "rust-overlay": {
       "inputs": {
-        "flake-utils": [
-          "flake-utils"
-        ],
         "nixpkgs": [
           "nixpkgs"
         ]
       },
       "locked": {
-        "lastModified": 1713150335,
-        "narHash": "sha256-Ic7zCPfiSYc9nFFp+E44WFk3TBJ99J/uPZ4QXX+uPPw=",
+        "lastModified": 1727490462,
+        "narHash": "sha256-OrrPiNBiikv9BR464XTT75FzOq7tKAvMbMi7YOKVIeg=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "b186d85e747e2b7bee220ec95839fb66c868dc47",
+        "rev": "11a13e50debafae4ae802f1d6b8585101516dd93",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index 8487f2bd822..2858d641617 100644
--- a/flake.nix
+++ b/flake.nix
@@ -58,6 +58,7 @@
             xorg.libXrandr
             xorg.libXi
             xorg.libxcb
+            cargo-llvm-cov # to visualize code coverage
           ];
 
         # DevInputs are not necessary to build roc as a user
diff --git a/nix/default.nix b/nix/default.nix
index e54aa8a2acf..4ecc76165d3 100644
--- a/nix/default.nix
+++ b/nix/default.nix
@@ -14,7 +14,9 @@ let
     inherit rustPlatform;
     compile-deps = callPackage ./compile-deps.nix { };
     rust-shell =
-      (rustVersion.override { extensions = [ "rust-src" "rust-analyzer" ]; });
+      # llvm-tools-preview for code coverage with cargo-llvm-cov
+      (rustVersion.override { extensions = [ "rust-src" "rust-analyzer" "llvm-tools-preview"]; });
+
 
     # contains all rust crates in workspace.members of Cargo.toml
     roc-full = (callPackage ./builder.nix { }).roc-release;