diff --git a/CMakeLists.txt b/CMakeLists.txt
index 51fc76d..97f650b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -40,12 +40,8 @@ if(NOT MSVC)
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall")
 endif()
 
-# Define __FILENAME__ consistently across Operating Systems
-if(NOT ${CMAKE_SYSTEM_NAME} MATCHES "Windows")
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D__FILENAME__='\"$$(subst ${CMAKE_SOURCE_DIR}/,,$$(abspath $$<))\"'")
-else()
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D__FILENAME__=__FILE__")
-endif()
+# Define __FILENAME__
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -D__FILENAME__=__FILE__")