diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3098445..feec2cd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -50,7 +50,7 @@ set(CMAKE_CXX_EXTENSIONS OFF)
 if(MSVC)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W2")
 elseif(CMAKE_CXX_COMPILER_ID MATCHES "[Cc]lang" OR CMAKE_CXX_COMPILER_ID MATCHES "GNU")
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Werror -Wextra -Wshadow -Weffc++ -Wsign-compare -Wshadow -Wwrite-strings -Wpointer-arith -Winit-self -Wconversion -Wno-sign-conversion")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Werror -Wextra -Wshadow -Weffc++ -Wsign-compare -Wshadow -Wwrite-strings -Wpointer-arith -Winit-self -Wconversion -Wno-sign-conversion -Wsuggest-override")
 endif()
 
 add_library(cxxopts INTERFACE)
diff --git a/include/cxxopts.hpp b/include/cxxopts.hpp
index 88e8a02..6ec7998 100644
--- a/include/cxxopts.hpp
+++ b/include/cxxopts.hpp
@@ -951,7 +951,7 @@ namespace cxxopts
 
       CXXOPTS_NODISCARD
       std::shared_ptr<Value>
-      clone() const
+      clone() const override
       {
         return std::make_shared<standard_value<T>>(*this);
       }