diff --git a/tasks/update-buildpack-dependency/run.rb b/tasks/update-buildpack-dependency/run.rb
index 59f6a77cb..1d33c82ff 100755
--- a/tasks/update-buildpack-dependency/run.rb
+++ b/tasks/update-buildpack-dependency/run.rb
@@ -157,6 +157,7 @@ def is_null(value)
 # Special Nginx stuff (for Nginx buildpack)
 # * There are two version lines, stable & mainline
 #   when we add a new minor line, we should update the version line regex
+nginx_files_to_edit = {}
 if !rebuilt && manifest_name == 'nginx' && buildpack_name == 'nginx'
   v = SemVer.parse(resource_version)
   raise "Invalid version format: #{resource_version}" if v.nil?
@@ -169,6 +170,84 @@ def is_null(value)
     manifest['version_lines']['mainline'] = data['source']['version_filter'].downcase
   end
 
+  # Update nginx integration test expectations
+  # The test file contains hardcoded version strings that need to match the manifest
+  test_file_path = 'src/nginx/integration/default_test.go'
+  full_test_file_path = File.join('buildpack', test_file_path)
+  if File.exist?(full_test_file_path)
+    test_content = File.read(full_test_file_path)
+    
+    # Get mainline and stable major.minor versions from version_lines
+    mainline_version = manifest['version_lines']['mainline']
+    stable_version = manifest['version_lines']['stable']
+    
+    # Extract unique version lines (X.Y.x format) from dependencies
+    version_lines = manifest['dependencies']
+      .select { |dep| dep['name'] == 'nginx' }
+      .map { |dep| dep['version'] }
+      .map { |ver| ver.match(/^(\d+\.\d+)\./) }
+      .compact
+      .map { |m| "#{m[1]}.x" }
+      .uniq
+      .sort_by { |v| Gem::Version.new(v.sub(/\.x$/, '.0')) }
+    
+    # Create the available versions string: "mainline, stable, 1.26.x, 1.28.x, 1.29.x"
+    available_versions = (['mainline', 'stable'] + version_lines).join(', ')
+    
+    # Update test expectations
+    # 1. Update "using mainline => X.Y." pattern
+    test_content.gsub!(/using mainline => \d+\.\d+\./, "using mainline => #{mainline_version.sub(/\.x$/, '.')}") if mainline_version
+    
+    # 2. Update "mainline => X.Y." pattern (for explicit mainline request)
+    test_content.gsub!(/Requested nginx version: mainline => \d+\.\d+\./, "Requested nginx version: mainline => #{mainline_version.sub(/\.x$/, '.')}") if mainline_version
+    
+    # 3. Update "stable => X.Y." pattern
+    test_content.gsub!(/stable => \d+\.\d+\./, "stable => #{stable_version.sub(/\.x$/, '.')}") if stable_version
+    
+    # 4. Update "Available versions: ..." line
+    test_content.gsub!(/Available versions: [^\`]+/, "Available versions: #{available_versions}")
+    
+    nginx_files_to_edit[test_file_path] = test_content
+    puts "Prepared nginx test expectations update for #{test_file_path}"
+    puts "  Mainline: #{mainline_version}"
+    puts "  Stable: #{stable_version}"
+    puts "  Available versions: #{available_versions}"
+  else
+    puts "Warning: nginx test file not found at #{full_test_file_path}"
+  end
+
+  # Update nginx override buildpack fixture
+  # The override buildpack test uses a fake nginx version to test error handling
+  # The version needs to match the current mainline version line
+  override_file_path = 'fixtures/util/override_buildpack/override.yml'
+  full_override_file_path = File.join('buildpack', override_file_path)
+  if File.exist?(full_override_file_path)
+    override_content = File.read(full_override_file_path)
+    
+    mainline_version = manifest['version_lines']['mainline']
+    
+    # Extract the major.minor from mainline (e.g., "1.28.x" -> "1.28")
+    if mainline_version && mainline_version.match(/^(\d+\.\d+)/)
+      mainline_major_minor = $1
+      fake_version = "#{mainline_major_minor}.999"  # e.g., "1.28.999"
+      
+      # Update version_lines.mainline
+      override_content.gsub!(/^(\s*mainline:\s+)\d+\.\d+\.\d+/, "\\1#{fake_version}")
+      
+      # Update nginx dependency version
+      override_content.gsub!(/^(\s*version:\s+)\d+\.\d+\.\d+/, "\\1#{fake_version}")
+      
+      # Update URI
+      override_content.gsub!(/nginx-\d+\.\d+\.\d+/, "nginx-#{fake_version}")
+      
+      nginx_files_to_edit[override_file_path] = override_content
+      puts "Prepared override buildpack fixture update for #{override_file_path}"
+      puts "  Fake version: #{fake_version}"
+    end
+  else
+    puts "Warning: override buildpack fixture not found at #{full_override_file_path}"
+  end
+
 end
 
 #
@@ -284,5 +363,12 @@ def is_null(value)
     end
   end
 
+  nginx_files_to_edit.each do |path, content|
+    if content
+      File.write(path, content)
+      GitClient.add_file(path)
+    end
+  end
+
   GitClient.safe_commit(commit_message.to_s)
 end