diff --git a/CMakeLists.txt b/CMakeLists.txt
index f6b7edf..f122c0b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -17,6 +17,7 @@ set(XTEST_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 
 function(add_xtest_executable TARGET)
     add_executable(${TARGET} ${ARGN})
+    target_compile_definitions(${TARGET} PRIVATE XTEST)
     target_include_directories(${TARGET} AFTER PRIVATE "${XTEST_SOURCE_DIR}/include/xtest")
     target_include_directories(${TARGET} SYSTEM BEFORE PRIVATE "${XTEST_SOURCE_DIR}/include/xtest-assert")
     target_link_libraries(${TARGET} xtest)