diff --git a/LeanCopilot/Tactics.lean b/LeanCopilot/Tactics.lean
index a4319c5..5efe1f3 100644
--- a/LeanCopilot/Tactics.lean
+++ b/LeanCopilot/Tactics.lean
@@ -134,7 +134,7 @@ elab_rules : tactic
     let tactics := tacticsWithScores.map (·.1)
     if ← isVerbose then
       logInfo s!"Tactics: {tactics}"
-    let range : String.Range := { start := tac.getRange?.get!.start, stop := pfx.raw.getRange?.get!.stop }
+    let range : Lean.Syntax.Range := { start := tac.getRange?.get!.start, stop := pfx.raw.getRange?.get!.stop }
     let ref := Syntax.ofRange range
     hint ref tactics (← SuggestTactics.checkTactics)
 
diff --git a/README.md b/README.md
index 4c262af..bfec8ea 100644
--- a/README.md
+++ b/README.md
@@ -61,7 +61,7 @@ moreLinkArgs = ["-L./.lake/packages/LeanCopilot/.lake/build/lib", "-lctranslate2
 require LeanCopilot from git "https://github.com/lean-dojo/LeanCopilot.git" @ "LEAN_COPILOT_VERSION"
 ```
 
-For stable Lean versions (e.g., `v4.25.0`), set `LEAN_COPILOT_VERSION` to be that version. For the latest unstable Lean versions (e.g., `v4.26.0-rc1`), set `LEAN_COPILOT_VERSION` to `main`. In either case, make sure the version is compatible with other dependencies such as mathlib. If your project uses lakefile.toml instead of lakefile.lean, it should include:
+For stable Lean versions (e.g., `v4.26.0`), set `LEAN_COPILOT_VERSION` to be that version. For the latest unstable Lean versions (e.g., `v4.27.0-rc1`), set `LEAN_COPILOT_VERSION` to `main`. In either case, make sure the version is compatible with other dependencies such as mathlib. If your project uses lakefile.toml instead of lakefile.lean, it should include:
 
 ```toml
 [[require]]
diff --git a/lake-manifest.json b/lake-manifest.json
index 0e907fc..e02a3b3 100644
--- a/lake-manifest.json
+++ b/lake-manifest.json
@@ -5,20 +5,20 @@
    "type": "git",
    "subDir": null,
    "scope": "",
-   "rev": "26e4c7c0e63eb3e6cce3cf7faba27b8526ea8349",
+   "rev": "2f6d238744c4cb07fdc91240feaf5d4221a27931",
    "name": "aesop",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "master",
+   "inputRev": "2f6d238744c4cb07fdc91240feaf5d4221a27931",
    "inherited": false,
    "configFile": "lakefile.toml"},
   {"url": "https://github.com/leanprover-community/batteries.git",
    "type": "git",
    "subDir": null,
    "scope": "",
-   "rev": "5c78955e8375f872c085514cb521216bac1bda17",
+   "rev": "24241822ef9d3e7f6a3bcc53ad136e12663db8f3",
    "name": "batteries",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "main",
+   "inputRev": "24241822ef9d3e7f6a3bcc53ad136e12663db8f3",
    "inherited": false,
    "configFile": "lakefile.toml"}],
  "name": "LeanCopilot",
diff --git a/lakefile.lean b/lakefile.lean
index b466d88..99d8bc2 100644
--- a/lakefile.lean
+++ b/lakefile.lean
@@ -422,8 +422,8 @@ extern_lib libleanffi pkg := do
   buildStaticLib (pkg.sharedLibDir / name) #[ct2O]
 
 
-require batteries from git "https://github.com/leanprover-community/batteries.git" @ "main"
-require aesop from git "https://github.com/leanprover-community/aesop" @ "master"
+require batteries from git "https://github.com/leanprover-community/batteries.git" @ "24241822ef9d3e7f6a3bcc53ad136e12663db8f3"
+require aesop from git "https://github.com/leanprover-community/aesop" @ "2f6d238744c4cb07fdc91240feaf5d4221a27931"
 
 meta if get_config? env = some "dev" then -- dev is so not everyone has to build it
 require «doc-gen4» from git "https://github.com/leanprover/doc-gen4" @ "main"
diff --git a/lean-toolchain b/lean-toolchain
index 1d4c9d4..2654c20 100644
--- a/lean-toolchain
+++ b/lean-toolchain
@@ -1 +1 @@
-leanprover/lean4:v4.25.0
\ No newline at end of file
+leanprover/lean4:v4.26.0
\ No newline at end of file