diff --git a/flake.lock b/flake.lock
index c2be67aca..24af11d6e 100644
--- a/flake.lock
+++ b/flake.lock
@@ -35,16 +35,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1730831018,
-        "narHash": "sha256-2S0HwIFRxYp+afuoFORcZA9TjryAf512GmE0MTfEOPU=",
+        "lastModified": 1732310578,
+        "narHash": "sha256-kk5Cv6wB20ujrB8w2ny5Co20xCHYOjUSyk2VRuP0sZw=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "8c4dc69b9732f6bbe826b5fbb32184987520ff26",
+        "rev": "72f68849662579c8d4e5d13bd4d400723a1d8edd",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixpkgs-unstable",
+        "ref": "nixos-unstable-small",
         "repo": "nixpkgs",
         "type": "github"
       }
diff --git a/flake.nix b/flake.nix
index 719b49369..62aeae67f 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,6 +1,9 @@
 {
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    # TODO: switch back once nix 2.25 hits nixpkgs-unstable
+    # https://nixpk.gs/pr-tracker.html?pr=355350
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable-small";
+    #nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
 
     flake-parts.url = "github:hercules-ci/flake-parts";
 
@@ -33,7 +36,7 @@
             callPackage
             stdenv
             ;
-          nix = nixVersions.nix_2_24;
+          nix = nixVersions.nix_2_25;
           llvmPackages = llvmPackages_16;
           nixf = callPackage ./libnixf { };
           nixt = callPackage ./libnixt { inherit nix; };
diff --git a/libnixt/test/Value.cpp b/libnixt/test/Value.cpp
index 30a2b8536..c597b41cc 100644
--- a/libnixt/test/Value.cpp
+++ b/libnixt/test/Value.cpp
@@ -58,7 +58,7 @@ TEST_F(ValueTest, selectAttrPath) {
   nix::Value &Kern = selectStringViews(*State, Nested, {"c", "d"});
 
   ASSERT_EQ(Kern.type(), nix::ValueType::nInt);
-  ASSERT_EQ(Kern.integer(), 1);
+  ASSERT_EQ(Kern.integer(), nix::NixInt{ 1 });
 }
 
 } // namespace
diff --git a/nixd/lib/Eval/AttrSetProvider.cpp b/nixd/lib/Eval/AttrSetProvider.cpp
index dd01a23f7..8acc933e3 100644
--- a/nixd/lib/Eval/AttrSetProvider.cpp
+++ b/nixd/lib/Eval/AttrSetProvider.cpp
@@ -54,8 +54,8 @@ std::optional<Location> locationOf(nix::PosTable &PTable, nix::Value &V) {
     return std::nullopt;
 
   Position LPos = {
-      .line = static_cast<int>(NixPos.line - 1),
-      .character = static_cast<int>(NixPos.column - 1),
+      .line = static_cast<long int>(NixPos.line - 1),
+      .character = static_cast<long int>(NixPos.column - 1),
   };
 
   return Location{
@@ -86,8 +86,8 @@ void fillUnsafeGetAttrPosLocation(nix::EvalState &State, nix::Value &V,
       Column.type() == nix::ValueType::nInt) {
 
     // Nix position starts from "1" however lsp starts from zero.
-    lspserver::Position Pos = {static_cast<int>(Line.integer()) - 1,
-                               static_cast<int>(Column.integer()) - 1};
+    lspserver::Position Pos = {static_cast<long int>(Line.integer()) - 1,
+                               static_cast<long int>(Column.integer()) - 1};
     Loc.range = {Pos, Pos};
   }
 }
diff --git a/nixd/lspserver/include/lspserver/Protocol.h b/nixd/lspserver/include/lspserver/Protocol.h
index 05959073c..400042759 100644
--- a/nixd/lspserver/include/lspserver/Protocol.h
+++ b/nixd/lspserver/include/lspserver/Protocol.h
@@ -127,12 +127,12 @@ bool fromJSON(const llvm::json::Value &, VersionedTextDocumentIdentifier &,
 
 struct Position {
   /// Line position in a document (zero-based).
-  int line = 0;
+  long int line = 0;
 
   /// Character offset on a line in a document (zero-based).
   /// WARNING: this is in UTF-16 codepoints, not bytes or characters!
   /// Use the functions in SourceCode.h to construct/interpret Positions.
-  int character = 0;
+  long int character = 0;
 
   friend bool operator==(const Position &LHS, const Position &RHS) {
     return std::tie(LHS.line, LHS.character) ==