diff --git a/cmake/FindCUDA.cmake b/cmake/FindCUDA.cmake
index ccfc4b93b3..f7502c7f27 100644
--- a/cmake/FindCUDA.cmake
+++ b/cmake/FindCUDA.cmake
@@ -538,7 +538,7 @@ if(NOT "${CUDA_TOOLKIT_ROOT_DIR}" STREQUAL "${CUDA_TOOLKIT_ROOT_DIR_INTERNAL}")
 endif()
 
 if(NOT "${CUDA_TARGET_TRIPLET}" STREQUAL "${CUDA_TARGET_TRIPLET_INTERNAL}" OR
-   NOT "${CUDA_TOOLKIT_TARGET_DIR}" STREQUAL "${CUDA_TOOLKIT_TARGET_DIR_INTERNAL}")
+   (DEFINED CUDA_TOOLKIT_TARGET_DIR AND NOT "${CUDA_TOOLKIT_TARGET_DIR}" STREQUAL "${CUDA_TOOLKIT_TARGET_DIR_INTERNAL}"))
   cuda_unset_include_and_libraries()
 endif()