diff --git a/lib/ruby_lsp/addon.rb b/lib/ruby_lsp/addon.rb
index c346d6ea6..230b87a65 100644
--- a/lib/ruby_lsp/addon.rb
+++ b/lib/ruby_lsp/addon.rb
@@ -56,26 +56,9 @@ def load_addons(global_state, outgoing_queue, include_project_addons: true)
         addon_files = Gem.find_files("ruby_lsp/**/addon.rb")
 
         if include_project_addons
-          project_addons = Dir.glob("#{global_state.workspace_path}/**/ruby_lsp/**/addon.rb")
           bundle_path = Bundler.bundle_path.to_s
-          gems_dir = Bundler.bundle_path.join("gems")
-
-          # Create an array of rejection glob patterns to ignore add-ons already discovered through Gem.find_files if
-          # they are also copied inside the workspace for whatever reason. We received reports of projects having gems
-          # installed in vendor/bundle despite BUNDLE_PATH pointing elsewhere. Without this mechanism, we will
-          # double-require the same add-on, potentially for different versions of the same gem, which leads to incorrect
-          # behavior
-          reject_glob_patterns = addon_files.map do |path|
-            relative_gem_path = Pathname.new(path).relative_path_from(gems_dir)
-            first_part, *parts = relative_gem_path.to_s.split(File::SEPARATOR)
-            first_part&.gsub!(/-([0-9.]+)$/, "*")
-            "**/#{first_part}/#{parts.join("/")}"
-          end
-
-          project_addons.reject! do |path|
-            path.start_with?(bundle_path) ||
-              reject_glob_patterns.any? { |pattern| File.fnmatch?(pattern, path, File::Constants::FNM_PATHNAME) }
-          end
+          project_addons = Dir.glob("#{global_state.workspace_path}/**/ruby_lsp/**/addon.rb")
+          project_addons.reject! { |path| path.start_with?(bundle_path) || gem_installation_path?(path) }
 
           addon_files.concat(project_addons)
         end
@@ -162,6 +145,23 @@ def depend_on_ruby_lsp!(*version_constraints)
             "Add-on is not compatible with this version of the Ruby LSP. Skipping its activation"
         end
       end
+
+      private
+
+      # Checks if a path appears to be inside a versioned gem installation directory (e.g., `rubocop-1.73.0/lib/...`) by
+      # looking for a directory segment matching `name-version` before the `lib` component
+      #
+      #: (String path) -> bool
+      def gem_installation_path?(path)
+        parts = path.split(%r{[/\\]})
+        lib_index = parts.rindex("lib")
+        return false unless lib_index
+
+        prefix = parts[0...lib_index] #: Array[String]?
+        return false unless prefix
+
+        prefix.any? { |part| part.match?(/-\d+(\.\d+)+$/) }
+      end
     end
 
     #: -> void
diff --git a/test/addon_test.rb b/test/addon_test.rb
index ffadeed2b..75ec3687e 100644
--- a/test/addon_test.rb
+++ b/test/addon_test.rb
@@ -255,9 +255,103 @@ def version
         Addon.load_addons(@global_state, @outgoing_queue)
 
         assert_raises(Addon::AddonNotFoundError) do
-          Addon.get("Project Addon", "0.1.0")
+          Addon.get("Old RuboCop Addon", "0.1.0")
         end
       end
     end
+
+    def test_loading_project_addons_ignores_old_gem_version_even_when_gem_is_not_in_bundle
+      # If there's an old installation of an add-on gem that has since been removed from the Gemfile, but not cleaned
+      # up, we must not require it
+
+      Dir.mktmpdir do |dir|
+        addon_dir = File.join(dir, "ruby-lsp-rails-0.3.6", "lib", "ruby_lsp", "rails")
+        FileUtils.mkdir_p(addon_dir)
+
+        File.write(File.join(addon_dir, "addon.rb"), <<~RUBY)
+          class OldRailsAddon < RubyLsp::Addon
+            def activate(global_state, outgoing_queue)
+            end
+
+            def name
+              "Old Rails Addon"
+            end
+
+            def version
+              "0.3.6"
+            end
+          end
+        RUBY
+
+        @global_state.apply_options({
+          workspaceFolders: [{ uri: URI::Generic.from_path(path: dir).to_s }],
+        })
+
+        Addon.load_addons(@global_state, @outgoing_queue)
+
+        assert_raises(Addon::AddonNotFoundError) do
+          Addon.get("Old Rails Addon", "0.3.6")
+        end
+      end
+    end
+
+    def test_loading_project_addons_ignores_double_addon_installation
+      # If there are two installations of the same gem inside of the project workspace, we should not load the incorrect
+      # one. We must always load the one coming from the bundle and ignore any others
+
+      Dir.mktmpdir do |dir|
+        addon_dir = File.join(dir, "vendor", "bundle", "rubocop-1.73.0", "lib", "ruby_lsp", "rubocop")
+        FileUtils.mkdir_p(addon_dir)
+
+        File.write(File.join(addon_dir, "addon.rb"), <<~RUBY)
+          $loaded_expected = true
+
+          class RuboCopAddon < RubyLsp::Addon
+            def activate(global_state, outgoing_queue)
+            end
+
+            def name
+              "RuboCop Addon"
+            end
+
+            def version
+              "0.1.0"
+            end
+          end
+        RUBY
+
+        addon_dir = File.join(dir, "custom_gems", "rubocop-1.68.0", "lib", "ruby_lsp", "rubocop")
+        FileUtils.mkdir_p(addon_dir)
+
+        File.write(File.join(addon_dir, "addon.rb"), <<~RUBY)
+          $loaded_incorrect = true
+
+          class RuboCopAddon < RubyLsp::Addon
+            def activate(global_state, outgoing_queue)
+            end
+
+            def name
+              "RuboCop Addon"
+            end
+
+            def version
+              "0.1.0"
+            end
+          end
+        RUBY
+
+        @global_state.apply_options({
+          workspaceFolders: [{ uri: URI::Generic.from_path(path: dir).to_s }],
+        })
+
+        expected_addon_path = File.join(dir, "vendor", "bundle", "rubocop-1.73.0", "lib", "ruby_lsp", "rubocop", "addon.rb")
+        Gem.stubs(:find_files).with("ruby_lsp/**/addon.rb").returns([expected_addon_path])
+        Bundler.stubs(:bundle_path).returns(Pathname.new(File.join(dir, "vendor", "bundle")))
+        Addon.load_addons(@global_state, @outgoing_queue)
+
+        refute($loaded_incorrect) # rubocop:disable Style/GlobalVars
+        assert($loaded_expected) # rubocop:disable Style/GlobalVars
+      end
+    end
   end
 end