diff --git a/drivers/include/periph/flashpage.h b/drivers/include/periph/flashpage.h
index c571fa1c8b..1634cc2744 100644
--- a/drivers/include/periph/flashpage.h
+++ b/drivers/include/periph/flashpage.h
@@ -238,6 +238,9 @@ void flashpage_erase(unsigned page);
 
 /**
  * @brief Get number of first free flashpage
+ * @deprecated Use @ref FLASH_WRITABLE_INIT instead, which is usable in modules
+ *             as well as applications. The function will be removed after
+ *             the 2022.04 release.
  *
  * If riotboot is used in two slot mode, this number will change across
  * firmware updates as the firmware slots alternate.
@@ -246,6 +249,9 @@ unsigned flashpage_first_free(void);
 
 /**
  * @brief Get number of last free flashpage
+ * @deprecated Use @ref FLASH_WRITABLE_INIT instead, which is usable in modules
+ *             as well as applications. The function will be removed after
+ *             the 2022.04 release.
  *
  * If riotboot is used in two slot mode, this number will change across
  * firmware updates as the firmware slots alternate.