diff --git a/pkgs/development/ruby-modules/with-packages/Gemfile b/pkgs/development/ruby-modules/with-packages/Gemfile
index 55f958356b6c..b6cfd674cfcf 100644
--- a/pkgs/development/ruby-modules/with-packages/Gemfile
+++ b/pkgs/development/ruby-modules/with-packages/Gemfile
@@ -49,6 +49,7 @@ gem 'digest-sha3'
 gem 'dip'
 gem 'domain_name'
 gem 'do_sqlite3'
+gem 'erb-formatter'
 gem 'ethon'
 gem 'eventmachine'
 gem 'excon'
diff --git a/pkgs/top-level/ruby-packages.nix b/pkgs/top-level/ruby-packages.nix
index e2b3be5e639e..922b5789fbc6 100644
--- a/pkgs/top-level/ruby-packages.nix
+++ b/pkgs/top-level/ruby-packages.nix
@@ -886,6 +886,17 @@
     };
     version = "0.5.3";
   };
+  erb-formatter = {
+    dependencies = ["syntax_tree"];
+    groups = ["default"];
+    platforms = [];
+    source = {
+      remotes = ["https://rubygems.org"];
+      sha256 = "1hr6q367ngnjjlclhjx8gma98dndmk04bj1pap5p5sqarn8ic01x";
+      type = "gem";
+    };
+    version = "0.4.3";
+  };
   erubi = {
     groups = ["default"];
     platforms = [];