diff --git a/source/CMakeLists.txt b/source/CMakeLists.txt
index b352314a..0fa63cf8 100644
--- a/source/CMakeLists.txt
+++ b/source/CMakeLists.txt
@@ -31,7 +31,7 @@ elseif(CMAKE_CXX_COMPILER_ID MATCHES "GNU")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wno-unknown-pragmas")
 elseif(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror -Wno-c++98-compat -Wno-c++98-compat-pedantic -Wno-padded -Wno-documentation-unknown-command -Wno-unknown-pragmas")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DNDEBUG -Werror -Wno-c++98-compat -Wno-c++98-compat-pedantic -Wno-padded -Wno-documentation-unknown-command -Wno-unknown-pragmas")
 endif()
 
 if(APPLE)