diff --git a/CMakeLists.txt b/CMakeLists.txt
index d1f8a13fb9f..63a2f74404c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1190,10 +1190,6 @@ if(APPLE)
   append_cxx_flag_if_supported("-Wno-missing-braces" CMAKE_CXX_FLAGS)
 endif()
 
-if(USE_XPU)
-  string(APPEND CMAKE_CXX_FLAGS " -DUSE_XPU")
-endif()
-
 if(EMSCRIPTEN)
   string(
     APPEND
diff --git a/cmake/public/xpu.cmake b/cmake/public/xpu.cmake
index be083cb93af..b39e31d0ade 100644
--- a/cmake/public/xpu.cmake
+++ b/cmake/public/xpu.cmake
@@ -11,6 +11,7 @@ set(XPU_HOST_CXX_FLAGS)
 find_package(SYCLToolkit REQUIRED)
 if(NOT SYCL_FOUND)
   set(PYTORCH_FOUND_XPU FALSE)
+  # Exit early to avoid populating XPU_HOST_CXX_FLAGS.
   return()
 endif()
 set(PYTORCH_FOUND_XPU TRUE)
@@ -36,6 +37,8 @@ torch_xpu_get_arch_list(XPU_ARCH_FLAGS)
 # propagate to torch-xpu-ops
 set(TORCH_XPU_ARCH_LIST ${XPU_ARCH_FLAGS})
 
+# Ensure USE_XPU is enabled.
+string(APPEND XPU_HOST_CXX_FLAGS " -DUSE_XPU")
 string(APPEND XPU_HOST_CXX_FLAGS " -DSYCL_COMPILER_VERSION=${SYCL_COMPILER_VERSION}")
 
 if(DEFINED ENV{XPU_ENABLE_KINETO})