diff --git a/include/ircd/ios.h b/include/ircd/ios.h
index cfed73d5f..8a9877b50 100644
--- a/include/ircd/ios.h
+++ b/include/ircd/ios.h
@@ -110,8 +110,8 @@ struct ircd::ios::descriptor
 	string_view name;
 	uint64_t id {++ids};
 	std::unique_ptr<struct stats> stats;
-	std::function<void *(handler &, const size_t &)> allocator;
-	std::function<void (handler &, void *const &, const size_t &)> deallocator;
+	void *(*allocator)(handler &, const size_t &);
+	void (*deallocator)(handler &, void *const &, const size_t &);
 	std::vector<std::array<uint64_t, 2>> history; // epoch, cycles
 	uint8_t history_pos {0};
 	bool continuation {false};
diff --git a/ircd/fs_aio.cc b/ircd/fs_aio.cc
index b464f4272..8bc16a812 100644
--- a/ircd/fs_aio.cc
+++ b/ircd/fs_aio.cc
@@ -1120,7 +1120,7 @@ ircd::fs::aio::system::handle_descriptor
 	// appears to excessively allocate and deallocate 120 bytes; this
 	// is a simple asynchronous operation, we can do better (and perhaps
 	// even better than this below).
-	[](auto &handler, const size_t &size)
+	[](ios::handler &handler, const size_t &size) -> void *
 	{
 		assert(ircd::fs::aio::system);
 		auto &system(*ircd::fs::aio::system);
@@ -1136,7 +1136,7 @@ ircd::fs::aio::system::handle_descriptor
 	},
 
 	// no deallocation; satisfied by class member unique_ptr
-	[](auto &handler, void *const &ptr, const auto &size) {},
+	[](ios::handler &handler, void *const &ptr, const size_t &size) {},
 
 	// continuation
 	true,
diff --git a/ircd/fs_iou.cc b/ircd/fs_iou.cc
index 003a6c071..49b3b9496 100644
--- a/ircd/fs_iou.cc
+++ b/ircd/fs_iou.cc
@@ -520,7 +520,7 @@ ircd::fs::iou::system::handle_descriptor
 	// appears to excessively allocate and deallocate 120 bytes; this
 	// is a simple asynchronous operation, we can do better (and perhaps
 	// even better than this below).
-	[](auto &handler, const size_t &size)
+	[](ios::handler &handler, const size_t &size) -> void *
 	{
 		assert(ircd::fs::iou::system);
 		auto &system(*ircd::fs::iou::system);
@@ -536,7 +536,7 @@ ircd::fs::iou::system::handle_descriptor
 	},
 
 	// no deallocation; satisfied by class member unique_ptr
-	[](auto &handler, void *const &ptr, const auto &size) {}
+	[](ios::handler &handler, void *const &ptr, const size_t &size) -> void {}
 };
 
 /// Handle notifications that requests are complete.