diff --git a/cpp/src/arrow/io/memory.cc b/cpp/src/arrow/io/memory.cc
index 1cde5e64e01..361895494e1 100644
--- a/cpp/src/arrow/io/memory.cc
+++ b/cpp/src/arrow/io/memory.cc
@@ -54,7 +54,6 @@ BufferOutputStream::BufferOutputStream(const std::shared_ptr<ResizableBuffer>& b
 Result<std::shared_ptr<BufferOutputStream>> BufferOutputStream::Create(
     int64_t initial_capacity, MemoryPool* pool) {
   // ctor is private, so cannot use make_shared
-  DCHECK_NE(pool, nullptr);
   auto ptr = std::shared_ptr<BufferOutputStream>(new BufferOutputStream);
   RETURN_NOT_OK(ptr->Reset(initial_capacity, pool));
   return ptr;
diff --git a/cpp/src/jni/orc/jni_wrapper.cpp b/cpp/src/jni/orc/jni_wrapper.cpp
index a3419280e73..e6fc82312d5 100644
--- a/cpp/src/jni/orc/jni_wrapper.cpp
+++ b/cpp/src/jni/orc/jni_wrapper.cpp
@@ -226,7 +226,7 @@ Java_org_apache_arrow_adapter_orc_OrcStripeReaderJniWrapper_getSchema(JNIEnv* en
 
   auto schema = stripe_reader->schema();
 
-  auto maybe_buffer = arrow::ipc::SerializeSchema(*schema, nullptr);
+  auto maybe_buffer = arrow::ipc::SerializeSchema(*schema, arrow::default_memory_pool());
   if (!maybe_buffer.ok()) {
     return nullptr;
   }