diff --git a/var/spack/repos/builtin/packages/sundials/package.py b/var/spack/repos/builtin/packages/sundials/package.py
index 3708e34d492..8f025724306 100644
--- a/var/spack/repos/builtin/packages/sundials/package.py
+++ b/var/spack/repos/builtin/packages/sundials/package.py
@@ -398,6 +398,7 @@ def cmake_args(self):
 
         if "+cuda" in spec:
             args.append(define("CMAKE_CUDA_ARCHITECTURES", spec.variants["cuda_arch"].value))
+            args.append(define("CUDAToolkit_ROOT", self.spec["cuda"].prefix))
 
         if "+rocm" in spec:
             args.extend(