diff --git a/include/libcamera/internal/control_serializer.h
b/include/libcamera/internal/control_serializer.h
index 99e57fee..a38ca6b0 100644
--- a/include/libcamera/internal/control_serializer.h
+++ b/include/libcamera/internal/control_serializer.h
@@ -47,9 +47,9 @@ private:
 	static void store(const ControlValue &value, ByteStreamBuffer &buffer);
 	static void store(const ControlInfo &info, ByteStreamBuffer &buffer);

-	ControlValue loadControlValue(ControlType type, ByteStreamBuffer &buffer,
+	ControlValue loadControlValue(ByteStreamBuffer &buffer,
 				      bool isArray = false, unsigned int count = 1);
-	ControlInfo loadControlInfo(ControlType type, ByteStreamBuffer &buffer);
+	ControlInfo loadControlInfo(ByteStreamBuffer &buffer);

 	unsigned int serial_;
 	unsigned int serialSeed_;
diff --git a/src/libcamera/control_serializer.cpp
b/src/libcamera/control_serializer.cpp
index e87d2362..0cf719bd 100644
--- a/src/libcamera/control_serializer.cpp
+++ b/src/libcamera/control_serializer.cpp
@@ -144,7 +144,7 @@ void ControlSerializer::reset()

 size_t ControlSerializer::binarySize(const ControlValue &value)
 {
-	return value.data().size_bytes();
+	return sizeof(ControlType) + value.data().size_bytes();
 }

 size_t ControlSerializer::binarySize(const ControlInfo &info)
@@ -195,6 +195,8 @@ size_t ControlSerializer::binarySize(const
ControlList &list)
 void ControlSerializer::store(const ControlValue &value,
 			      ByteStreamBuffer &buffer)
 {
+	const ControlType type = value.type();
+	buffer.write(&type);
 	buffer.write(value.data());
 }