diff --git a/ruby/package-fn.nix b/ruby/package-fn.nix
index 9f07b8c..4bbf119 100644
--- a/ruby/package-fn.nix
+++ b/ruby/package-fn.nix
@@ -67,6 +67,12 @@ let
     # Have `configure' avoid `/usr/bin/nroff' in non-chroot builds.
     NROFF = if docSupport then "${groff}/bin/nroff" else null;
 
+    LANG =
+      if docSupport && (with versionComparison version; hasPrefix "4.0") then
+        "C.UTF-8"
+      else
+        null;
+
     nativeBuildInputs = [
       bison
     ] ++ ops (stdenv.buildPlatform != stdenv.hostPlatform) [ buildPackages.ruby ];
diff --git a/ruby/versions.json b/ruby/versions.json
index 6a6695b..93e8447 100644
--- a/ruby/versions.json
+++ b/ruby/versions.json
@@ -987,14 +987,18 @@
     "4.0.3": {
       "url": "https://cache.ruby-lang.org/pub/ruby/4.0/ruby-4.0.3.tar.gz",
       "sha256": "77964acc370d5c8375b9502e5ba6c13c03ef91ab9eb9f521c84fb42b9c9a6b0f"
+    },
+    "4.0.4": {
+      "url": "https://cache.ruby-lang.org/pub/ruby/4.0/ruby-4.0.4.tar.gz",
+      "sha256": "f35f6edfa3dabb3f723f9d0cf1906c6512ae77f4e412ab1e68cc6e91d230fa80"
     }
   },
   "aliases": {
     "2": "2.7.8",
     "3": "3.4.9",
-    "4": "4.0.3",
-    "latest": "4.0.3",
-    "4.0": "4.0.3",
+    "4": "4.0.4",
+    "latest": "4.0.4",
+    "4.0": "4.0.4",
     "3.4": "3.4.9",
     "3.3": "3.3.10",
     "3.2": "3.2.10",
@@ -1009,8 +1013,8 @@
     "2.1": "2.1.10",
     "2.*": "2.7.8",
     "3.*": "3.4.9",
-    "4.*": "4.0.3",
-    "4.0.*": "4.0.3",
+    "4.*": "4.0.4",
+    "4.0.*": "4.0.4",
     "3.4.*": "3.4.9",
     "3.3.*": "3.3.10",
     "3.2.*": "3.2.10",