diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0ab692d..6ca3f0c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -85,7 +85,11 @@ if (NOT WIN32)
 endif (NOT WIN32)
 
 set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -DDEBUG")
-set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -D__FNAME__='\"$(subst ${CMAKE_SOURCE_DIR}/,,$(abspath $<))\"'")
+if (NOT MSVC)
+	set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -D__FNAME__='\"$(subst ${CMAKE_SOURCE_DIR}/,,$(abspath $<))\"'")
+else (NOT MSVC)
+	set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -D__FNAME__=__FILE__")
+endif (NOT MSVC)
 
 # PROGRAMS:
 add_executable(breakhack