diff --git a/pkgs/by-name/pa/paperless-ngx/package.nix b/pkgs/by-name/pa/paperless-ngx/package.nix
index d05b49ca16e2..3a1fa7f93294 100644
--- a/pkgs/by-name/pa/paperless-ngx/package.nix
+++ b/pkgs/by-name/pa/paperless-ngx/package.nix
@@ -314,7 +314,7 @@ python.pkgs.buildPythonApplication rec {
       ;
     nltkData = with nltk-data; [
       punkt-tab
-      snowball_data
+      snowball-data
       stopwords
     ];
     tests = { inherit (nixosTests) paperless; };
diff --git a/pkgs/tools/text/nltk-data/default.nix b/pkgs/tools/text/nltk-data/default.nix
index 96125bd351f2..1ee377e4757b 100644
--- a/pkgs/tools/text/nltk-data/default.nix
+++ b/pkgs/tools/text/nltk-data/default.nix
@@ -76,7 +76,7 @@ lib.makeScope newScope (self: {
     location = "taggers";
     hash = "sha256-tl3Cn2okhBkUtTXvAmFRx72Brez6iTGRdmFTwFmpk3M=";
   };
-  snowball_data = makeNltkDataPackage {
+  snowball-data = makeNltkDataPackage {
     pname = "snowball_data";
     location = "stemmers";
     hash = "sha256-mNefwOPVJGz9kXV3LV4DuV7FJpNir/Nwg4ujd0CogEk=";
diff --git a/pkgs/top-level/aliases.nix b/pkgs/top-level/aliases.nix
index 6585e44b1b47..07d2bfb5a6d2 100644
--- a/pkgs/top-level/aliases.nix
+++ b/pkgs/top-level/aliases.nix
@@ -1352,6 +1352,7 @@ mapAliases {
   nltk-data.averaged_perceptron_tagger = nltk-data.averaged-perceptron-tagger; # Added 2025-05-21
   nltk-data.averaged_perceptron_tagger_eng = nltk-data.averaged-perceptron-tagger-eng; # Added 2025-05-21
   nltk-data.punkt_tab = nltk-data.punkt-tab; # Added 2025-05-21
+  nltk-data.snowball_data = nltk-data.snowball-data; # Added 2025-05-21
   nmap-unfree = throw "'nmap-unfree' has been renamed to/replaced by 'nmap'"; # Converted to throw 2024-10-17
   noah = throw "'noah' has been removed because it was broken and its upstream archived"; # Added 2025-05-10
   nodejs_18 = throw "Node.js 18.x has reached End-Of-Life and has been removed"; # Added 2025-04-23