diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3d454ab..be5aead 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,6 +5,10 @@ set(CMAKE_C_STANDARD_REQUIRED ON)
 set(CMAKE_C_EXTENSIONS OFF)
 set(CMAKE_C_STANDARD 11)
 
+set_property(DIRECTORY . APPEND PROPERTY COMPILE_DEFINITIONS
+  $<$<CONFIG:Debug>:_DEBUG>
+  )
+
 set(CMAKE_C_FLAGS "-Wall -Werror ${CMAKE_C_FLAGS}")
 
 find_package(Threads REQUIRED)