diff --git a/flake.lock b/flake.lock
index 2e01d446e..2b5bc7d65 100644
--- a/flake.lock
+++ b/flake.lock
@@ -22,16 +22,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1767313136,
-        "narHash": "sha256-16KkgfdYqjaeRGBaYsNrhPRRENs0qzkQVUooNHtoy2w=",
+        "lastModified": 1779971959,
+        "narHash": "sha256-R5nauXyqyfRUFiZycFFZdkF7wl6eaUpPLst35+2nJQY=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "ac62194c3917d5f474c1a844b6fd6da2db95077d",
+        "rev": "ec942ba042dad5ef097e2ef3a3effc034241f011",
         "type": "github"
       },
       "original": {
         "owner": "nixos",
-        "ref": "nixos-25.05",
+        "ref": "nixos-26.05",
         "repo": "nixpkgs",
         "type": "github"
       }
diff --git a/flake.nix b/flake.nix
index 4756f201f..4e18d4616 100644
--- a/flake.nix
+++ b/flake.nix
@@ -2,7 +2,7 @@
   description = "Nix devshells for XiangShan";
 
   inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs/nixos-25.05";
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-26.05";
     gsim = {
       url = "github:OpenXiangShan/gsim";
       inputs.nixpkgs.follows = "nixpkgs";
@@ -49,16 +49,12 @@
         # compile verilator with clang instead of gcc
         ((verilator.override { stdenv = clangStdenv; }).overrideAttrs (finalAttrs: previousAttrs: {
           version = "5.048";
-          VERILATOR_SRC_VERSION = "v${finalAttrs.version}";
           src = fetchFromGitHub {
             owner = "verilator";
             repo = "verilator";
             rev = "v${finalAttrs.version}";
             hash = "sha256-xvqqgbW7L07+NBYzGN2KLhwir58ByShxo4VVPI3pgZk=";
           };
-          # drop patch https://github.com/NixOS/nixpkgs/commit/06be23d66287c004cb8ef933a9ff6589276ab104
-          # since it's already included in 5.044
-          patches = [];
           # use jemalloc by default
           buildInputs = previousAttrs.buildInputs ++ [
             jemalloc
@@ -68,7 +64,12 @@
         gsim.packages.${system}.default
 
         # === debug ===
-        gtkwave
+        (gtkwave.overrideAttrs (finalAttrs: previousAttrs: {
+          # disable judy, it will cause a "abort: buffer overflow detected" error while opening xiangshan .fst waveforms
+          configureFlags = builtins.filter (
+            flag: flag != "--enable-judy"
+          ) previousAttrs.configureFlags;
+        }))
 
         # === lib ===
         readline