diff --git a/src/system/EventFD.cxx b/src/system/EventFD.cxx
index b3a740165..c567a141e 100644
--- a/src/system/EventFD.cxx
+++ b/src/system/EventFD.cxx
@@ -3,6 +3,7 @@
 
 #include "EventFD.hxx"
 #include "system/Error.hxx"
+#include "util/SpanCast.hxx"
 
 #include <cassert>
 
@@ -31,5 +32,5 @@ EventFD::Write() noexcept
 
 	static constexpr eventfd_t value = 1;
 	[[maybe_unused]] ssize_t nbytes =
-		fd.Write(&value, sizeof(value));
+		fd.Write(ReferenceAsBytes(value));
 }
diff --git a/src/system/SignalFD.cxx b/src/system/SignalFD.cxx
index ba3c4d058..72d1da05a 100644
--- a/src/system/SignalFD.cxx
+++ b/src/system/SignalFD.cxx
@@ -3,6 +3,7 @@
 
 #include "SignalFD.hxx"
 #include "Error.hxx"
+#include "util/SpanCast.hxx"
 
 #include <cassert>
 
@@ -28,7 +29,7 @@ SignalFD::Read() noexcept
 	assert(fd.IsDefined());
 
 	signalfd_siginfo info;
-	return fd.Read(&info, sizeof(info)) > 0
+	return fd.Read(ReferenceAsWritableBytes(info)) > 0
 		? info.ssi_signo
 		: -1;
 }