diff --git a/include/libcamera/meson.build b/include/libcamera/meson.build
index 408b7acf152c..2911d4bf4ec7 100644
--- a/include/libcamera/meson.build
+++ b/include/libcamera/meson.build
@@ -14,6 +14,7 @@ libcamera_public_headers = files([
     'logging.h',
     'pixel_format.h',
     'request.h',
+    'sequence.h',
     'stream.h',
     'transform.h',
 ])
diff --git a/include/libcamera/sequence.h b/include/libcamera/sequence.h
new file mode 100644
index 000000000000..ad6e99726a4e
--- /dev/null
+++ b/include/libcamera/sequence.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include <optional>
+
+#include <libcamera/base/compiler.h>
+
+namespace libcamera {
+
+class Sequence
+{
+public:
+	__nodiscard int update(unsigned int seq);
+	void reset() { sequence_.reset(); }
+
+private:
+	std::optional<unsigned int> sequence_;
+};
+
+}; // namespace libcamera
+
diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
index 26912ca17819..ffdffeb4bfdc 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -38,6 +38,7 @@ libcamera_sources = files([
     'process.cpp',
     'pub_key.cpp',
     'request.cpp',
+    'sequence.cpp',
     'source_paths.cpp',
     'stream.cpp',
     'sysfs.cpp',
diff --git a/src/libcamera/sequence.cpp b/src/libcamera/sequence.cpp
new file mode 100644
index 000000000000..374b4f04d0a3
--- /dev/null
+++ b/src/libcamera/sequence.cpp
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2022, Ideas on Board Oy.
+ *
+ * sequence.cpp Sequence Number Observer
+ */
+
+#include <libcamera/base/log.h>
+
+#include <libcamera/sequence.h>
+
+/**
+ * \file sequence.h
+ * \brief Sequence number observer
+ */
+
+namespace libcamera {
+
+/**
+ * \class Sequence
+ * \brief Sequence number tracking which expects monotonically incrementing
+ *	  numbers
+ *
+ * The Sequence number observer is initialised with the first value it is given.
+ * It will return a difference of the expected update value, against the newly
+ * provided value - allowing the consumer to identify if a break in a sequence
+ * has occured.
+ */
+
+/**
+ * \brief Update the sequence observer with the latest value
+ * \param seq The latest value for the sequence
+ *
+ * This function will update the state of the Sequence observer and identify any
+ * non-monotonic increment or change that may occur and return the difference
+ * from the expected update value.
+ *
+ * The sequence is initialised to the first value passed into \a update.
+ *
+ * \return The number of drops in the sequence that were detected
+ */
+__nodiscard int Sequence::update(unsigned int seq)
+{
+	if (!sequence_)
+		sequence_ = seq - 1;
+
+	/*
+	 * Any update expects a single integer difference from
+	 * the previous value.
+	 */
+	int diff = seq - sequence_.value() - 1;
+
+	sequence_ = seq;
+
+	return diff;
+};
+
+/**
+ * \fn Sequence::reset
+ * \brief Resets the sequence observer
+ *
+ * Re-initialises the sequence observer so that any known break in the monotonic
+ * sequence is not reported.
+ */
+
+} /* namespace libcamera */