diff --git a/include/stdex/stream.hpp b/include/stdex/stream.hpp
index 5a9b93fee..a43874217 100644
--- a/include/stdex/stream.hpp
+++ b/include/stdex/stream.hpp
@@ -3568,6 +3568,7 @@ namespace stdex
 #endif
 				size_t available = m_size - m_offset;
 				if (length <= available) {
+					stdex_assert(m_data || !length);
 					memcpy(data, &m_data[m_offset], length);
 					m_offset += length;
 					m_state = state_t::ok;
@@ -3577,6 +3578,7 @@ namespace stdex
 					m_state = state_t::eof;
 					return 0;
 				}
+				stdex_assert(m_data || !available);
 				memcpy(data, &m_data[m_offset], available);
 				m_offset += available;
 				m_state = state_t::ok;
@@ -3609,6 +3611,7 @@ namespace stdex
 				}
 				size_t end_offset = stdex::add(m_offset, sizeof(T));
 				if (end_offset <= m_size) {
+					stdex_assert(m_data);
 					data = LE2HE(*reinterpret_cast<T*>(&m_data[m_offset]));
 					m_offset = end_offset;
 #if !CHECK_STREAM_STATE
@@ -3649,6 +3652,7 @@ namespace stdex
 				}
 				size_t end_offset = stdex::add(m_offset, sizeof(uint32_t));
 				if (end_offset <= m_size) {
+					stdex_assert(m_data);
 					uint32_t num_chars = LE2HE(*reinterpret_cast<uint32_t*>(&m_data[m_offset]));
 					m_offset = end_offset;
 					end_offset = stdex::add(m_offset, stdex::mul(num_chars, sizeof(T)));
@@ -3682,6 +3686,7 @@ namespace stdex
 					if (!ok()) _Unlikely_
 						return 0;
 				}
+				stdex_assert(m_data || !length);
 				memcpy(&m_data[m_offset], data, length);
 				m_offset = end_offset;
 				if (m_offset > m_size)
@@ -3704,6 +3709,7 @@ namespace stdex
 					if (!ok()) _Unlikely_
 						return;
 				}
+				stdex_assert(m_data || !amount);
 				memset(&m_data[m_offset], byte, amount);
 				m_offset = end_offset;
 				if (m_offset > m_size)
@@ -3739,6 +3745,7 @@ namespace stdex
 					if (!ok()) _Unlikely_
 						return *this;
 				}
+				stdex_assert(m_data);
 				(*reinterpret_cast<T*>(&m_data[m_offset])) = HE2LE(data);
 				m_offset = end_offset;
 				if (m_offset > m_size)
@@ -3782,6 +3789,7 @@ namespace stdex
 					if (!ok()) _Unlikely_
 						return *this;
 				}
+				stdex_assert(m_data);
 				auto p = &m_data[m_offset];
 				*reinterpret_cast<uint32_t*>(p) = HE2LE((uint32_t)num_chars);
 				memcpy(p + sizeof(uint32_t), data, size_chars);
@@ -3827,6 +3835,7 @@ namespace stdex
 					if (!ok()) _Unlikely_
 						return *this;
 				}
+				stdex_assert(m_data);
 				auto p = &m_data[m_offset];
 				*reinterpret_cast<uint32_t*>(p) = HE2LE((uint32_t)num_chars);
 				memcpy(p + sizeof(uint32_t), data.data(), size_chars);
@@ -3858,6 +3867,7 @@ namespace stdex
 					if (!ok()) _Unlikely_
 						return 0;
 					while (to_write) {
+						stdex_assert(m_data || !to_write);
 						num_read = stream.read(&m_data[dst_offset], to_write);
 						/*dst_size =*/ dst_offset += num_read;
 						num_copied += num_read;
@@ -3877,6 +3887,7 @@ namespace stdex
 						reserve(dst_size);
 						if (!ok()) _Unlikely_
 							break;
+						stdex_assert(m_data || !block_size);
 						num_read = stream.read(&m_data[dst_offset], block_size);
 						dst_size = dst_offset += num_read;
 						num_copied += num_read;
@@ -3989,6 +4000,7 @@ namespace stdex
 #if SET_FILE_OP_TIMES
 				m_atime = m_mtime = time_point::now();
 #endif
+				stdex_assert(m_data);
 				stdex_assert(offset + sizeof(T) < m_size);
 				(*reinterpret_cast<T*>(&m_data[offset])) = HE2LE(data);
 			}
@@ -4020,6 +4032,7 @@ namespace stdex
 			template <class T>
 			void get(_In_ fpos_t offset, _Out_ T & data)
 			{
+				stdex_assert(m_data);
 				stdex_assert(offset + sizeof(T) < m_size);
 				data = LE2HE(*(T*)(&m_data[offset]));
 #if SET_FILE_OP_TIMES