diff --git a/include/buffer_transfer_manager.h b/include/buffer_transfer_manager.h
index 7e3abd504..a5a2e5c7d 100644
--- a/include/buffer_transfer_manager.h
+++ b/include/buffer_transfer_manager.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <cstddef>
 #include <list>
 #include <memory>
 #include <unordered_map>
@@ -47,6 +48,9 @@ namespace detail {
 			alignas(std::max_align_t) payload_type data[]; // max_align to allow reinterpret_casting a pointer to this member to any buffer element pointer
 		};
 
+		// unique_frame_ptr assumes that the flexible payload member begins at exactly sizeof(Frame) bytes
+		static_assert(offsetof(data_frame, data) == sizeof(data_frame));
+
 		struct transfer_in {
 			node_id source_nid;
 			MPI_Request request;
diff --git a/include/command.h b/include/command.h
index e4256ad97..d26c97115 100644
--- a/include/command.h
+++ b/include/command.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <cstddef>
 #include <variant>
 
 #include "intrusive_graph.h"
@@ -237,5 +238,8 @@ namespace detail {
 		iterable_range<const command_id*> iter_dependencies() const { return {dependencies, dependencies + num_dependencies}; }
 	};
 
+	// unique_frame_ptr assumes that the flexible payload member begins at exactly sizeof(Frame) bytes
+	static_assert(offsetof(command_frame, dependencies) == sizeof(command_frame));
+
 } // namespace detail
 } // namespace celerity