diff --git a/cmake/CMakeLists.txt b/cmake/CMakeLists.txt
index a35671c461..f5f155de8a 100644
--- a/cmake/CMakeLists.txt
+++ b/cmake/CMakeLists.txt
@@ -437,7 +437,9 @@ if (onnxruntime_USE_CUDA)
   add_definitions(-DUSE_CUDA=1)
   enable_language(CUDA)
   set(CMAKE_CUDA_STANDARD 14)
-  file(TO_CMAKE_PATH ${onnxruntime_CUDA_HOME} CUDA_TOOLKIT_ROOT_DIR)
+  if (DEFINED onnxruntime_CUDA_HOME)
+    file(TO_CMAKE_PATH ${onnxruntime_CUDA_HOME} CUDA_TOOLKIT_ROOT_DIR)
+  endif ()
   file(TO_CMAKE_PATH ${onnxruntime_CUDNN_HOME} onnxruntime_CUDNN_HOME)
   find_package(CUDA 9.0 REQUIRED)
   include(cub)
@@ -498,4 +500,4 @@ if (onnxruntime_BUILD_UNIT_TESTS)
   # turned ON by the previous step when building a shared lib
   set(CMAKE_SKIP_BUILD_RPATH OFF)
   include(onnxruntime_unittests.cmake)
-endif()
\ No newline at end of file
+endif()