diff --git a/ImportGraph/RequiredModules.lean b/ImportGraph/RequiredModules.lean
index 5e90a90..b3a91e1 100644
--- a/ImportGraph/RequiredModules.lean
+++ b/ImportGraph/RequiredModules.lean
@@ -129,7 +129,7 @@ partial def Environment.transitivelyRequiredModules' (env : Environment) (module
     if verbose then
       IO.println s!"Processing module {m}"
     let mut r : BitVec N := 0
-    for n in env.header.moduleData[(env.header.moduleNames.getIdx? m).getD 0]!.constNames do
+    for n in env.header.moduleData[((env.header.moduleNames.indexOf? m).map Fin.val).getD 0]!.constNames do
       if ! n.isInternal then
       -- This is messy: Mathlib is big enough that writing a recursive function causes a stack overflow.
       -- So we use an explicit stack instead. We visit each constant twice:
@@ -162,7 +162,7 @@ partial def Environment.transitivelyRequiredModules' (env : Environment) (module
   return result
 where
   toBitVec {N : Nat} (s : NameSet) : BitVec N :=
-    s.fold (init := 0) (fun b n => b ||| BitVec.twoPow _ ((env.header.moduleNames.getIdx? n).getD 0))
+    s.fold (init := 0) (fun b n => b ||| BitVec.twoPow _ (((env.header.moduleNames.indexOf? n).map Fin.val).getD 0))
   toNameSet {N : Nat} (b : BitVec N) : NameSet :=
     env.header.moduleNames.zipWithIndex.foldl (init := {}) (fun s (n, i) => if b.getLsbD i then s.insert n else s)
 
diff --git a/lake-manifest.json b/lake-manifest.json
index d4ed67a..c15a19f 100644
--- a/lake-manifest.json
+++ b/lake-manifest.json
@@ -1,24 +1,24 @@
 {"version": "1.1.0",
  "packagesDir": ".lake/packages",
  "packages":
- [{"url": "https://github.com/leanprover/lean4-cli",
+ [{"url": "https://github.com/leanprover-community/batteries",
    "type": "git",
    "subDir": null,
-   "scope": "leanprover",
-   "rev": "0c8ea32a15a4f74143e4e1e107ba2c412adb90fd",
-   "name": "Cli",
+   "scope": "leanprover-community",
+   "rev": "58b15585c1480b5e9afcded83a36b8ea0a7d4a24",
+   "name": "batteries",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "main",
+   "inputRev": "nightly-testing",
    "inherited": false,
    "configFile": "lakefile.toml"},
-  {"url": "https://github.com/leanprover-community/batteries",
+  {"url": "https://github.com/leanprover/lean4-cli",
    "type": "git",
    "subDir": null,
-   "scope": "leanprover-community",
-   "rev": "2ed85f320805f9d3a455ced3b181562ed146bc20",
-   "name": "batteries",
+   "scope": "leanprover",
+   "rev": "0c8ea32a15a4f74143e4e1e107ba2c412adb90fd",
+   "name": "Cli",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "nightly-testing",
+   "inputRev": "main",
    "inherited": false,
    "configFile": "lakefile.toml"}],
  "name": "importGraph",
diff --git a/lean-toolchain b/lean-toolchain
index 44435e7..5c0b148 100644
--- a/lean-toolchain
+++ b/lean-toolchain
@@ -1 +1 @@
-leanprover/lean4:nightly-2024-11-14
\ No newline at end of file
+leanprover/lean4:nightly-2024-11-20
\ No newline at end of file