diff --git a/src/llama-context.cpp b/src/llama-context.cpp
index 93fd51df04..73432e5d04 100644
--- a/src/llama-context.cpp
+++ b/src/llama-context.cpp
@@ -66,7 +66,7 @@ llama_context::llama_context(
         for (size_t i = 0; i < params.n_samplers; ++i) {
             const auto & config = params.samplers[i];
 
-            if (llama_sampler_chain_get(config.sampler, -1) != nullptr) {
+            if (llama_sampler_chain_get(config.sampler, -1) == nullptr) {
                 throw std::runtime_error("the backend samplers must be of type llama_sampler_chain");
             }
 
@@ -922,6 +922,11 @@ bool llama_context::set_sampler(llama_seq_id seq_id, llama_sampler * sampler) {
 
     if (sampler && can_offload) {
         ggml_backend_buffer_type_t buft = ggml_backend_dev_buffer_type(model.dev_output());
+        auto * host_buft = ggml_backend_dev_host_buffer_type(model.dev_output());
+        if (host_buft) {
+            buft = host_buft;
+        }
+
         sampler->iface->backend_init(sampler, buft);
 
         sampling.samplers[seq_id] = sampler;