diff --git a/CMakeLists.txt b/CMakeLists.txt
index 57804cf..7a86854 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@ INCLUDE(CheckLibraryExists)
 INCLUDE(CheckFunctionExists)
 
 PROJECT(ubox C)
-ADD_DEFINITIONS(-Os -Wall -Werror --std=gnu99 -g3 -Wmissing-declarations)
+ADD_DEFINITIONS(-Os -Wextra -Wall -Werror --std=gnu99 -g3 -Wmissing-declarations -Wno-unused-parameter)
 
 OPTION(BUILD_LUA "build Lua plugin" ON)
 OPTION(BUILD_EXAMPLES "build examples" ON)