diff --git a/platforms/common/include/px4_platform_common/px4_mtd.h b/platforms/common/include/px4_platform_common/px4_mtd.h
index 71d9e577ff..fa792e78c4 100644
--- a/platforms/common/include/px4_platform_common/px4_mtd.h
+++ b/platforms/common/include/px4_platform_common/px4_mtd.h
@@ -80,6 +80,11 @@ __EXPORT ssize_t px4_mtd_get_partition_size(const mtd_instance_s *instance, cons
 int px4_at24c_initialize(FAR struct i2c_master_s *dev,
 			 uint8_t address, FAR struct mtd_dev_s **mtd_dev);
 
+/*
+  Update the page count of an already-initialised device.
+ */
+int px4_at24c_set_npages(FAR struct mtd_dev_s *dev, uint16_t npages);
+
 void px4_at24c_deinitialize(void);
 
 int flexspi_attach(mtd_instance_s *instance);
diff --git a/platforms/nuttx/src/px4/common/px4_24xxxx_mtd.c b/platforms/nuttx/src/px4/common/px4_24xxxx_mtd.c
index 65e5794a96..8d4e725ae0 100644
--- a/platforms/nuttx/src/px4/common/px4_24xxxx_mtd.c
+++ b/platforms/nuttx/src/px4/common/px4_24xxxx_mtd.c
@@ -618,6 +618,13 @@ int px4_at24c_initialize(FAR struct i2c_master_s *dev,
 	return 0;
 }
 
+int px4_at24c_set_npages(FAR struct mtd_dev_s *dev, uint16_t npages)
+{
+	FAR struct at24c_dev_s *priv = (FAR struct at24c_dev_s *)dev;
+	priv->npages = npages;
+	return 0;
+}
+
 /*
  * XXX: debug hackery
  */