diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5c27059..50b785a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,8 +6,8 @@ project(libprlearn VERSION 1.0.0 LANGUAGES CXX)
 if(NOT CMAKE_BUILD_TYPE)
     set(CMAKE_BUILD_TYPE Release)
 endif(NOT CMAKE_BUILD_TYPE)
-set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -Wall -Wpedantic")
-set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O3 -DNDEBUG -Wall -Wpedantic")
+set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -Wall -Wextra -Wpedantic")
+set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O3 -DNDEBUG -Wall -Wextra -Wpedantic")
 
 set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 set(CMAKE_CXX_STANDARD 17)
diff --git a/src/structs.h b/src/structs.h
index 88d39e7..6ca44fa 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -39,7 +39,10 @@ namespace prlearn {
         double _avg = 0;
         double _cnt = 0;
 
-        inline void addPoints(avg_t other) {
+        constexpr avg_t() = default;
+        constexpr avg_t(const avg_t&) = default;
+
+        inline void addPoints(const avg_t& other) {
             addPoints(other._cnt, other._avg);
         }
 
@@ -91,8 +94,7 @@ namespace prlearn {
 
     struct qvar_t : private avg_t {
 
-        qvar_t() {
-        };
+        qvar_t() = default;
 
         qvar_t(double d, double w, double v) {
             _avg = d;