diff --git a/Sources/HummingbirdMustache/Library.swift b/Sources/HummingbirdMustache/Library.swift
index 2593949..4b7a6c5 100644
--- a/Sources/HummingbirdMustache/Library.swift
+++ b/Sources/HummingbirdMustache/Library.swift
@@ -6,7 +6,7 @@ import Logging
 /// ```
 /// {{#sequence}}{{>entry}}{{/sequence}}
 /// ```
-public class HBMustacheLibrary {
+public final class HBMustacheLibrary {
     /// Initialize empty library
     public init() {
         templates = [:]
diff --git a/Sources/HummingbirdMustache/Template.swift b/Sources/HummingbirdMustache/Template.swift
index c2e5c54..d0f23e8 100644
--- a/Sources/HummingbirdMustache/Template.swift
+++ b/Sources/HummingbirdMustache/Template.swift
@@ -1,5 +1,5 @@
 /// Class holding Mustache template
-public class HBMustacheTemplate {
+public final class HBMustacheTemplate {
     /// Initialize template
     /// - Parameter string: Template text
     /// - Throws: HBMustacheTemplate.Error