diff --git a/os/kernel/include/chfiles.h b/os/kernel/include/chfiles.h
index c13af1349..e687811ea 100644
--- a/os/kernel/include/chfiles.h
+++ b/os/kernel/include/chfiles.h
@@ -46,10 +46,15 @@
 #ifndef _CHFILES_H_
 #define _CHFILES_H_
 
+/**
+ * @brief   No error return code.
+ */
+#define FILE_OK         0
+
 /**
  * @brief   Error code from the file stream methods.
  */
-#define FILE_ERROR 0xFFFFFFFFUL
+#define FILE_ERROR      0xFFFFFFFFUL
 
 /**
  * @brief   File offset type.
@@ -70,7 +75,7 @@ typedef uint32_t fileoffset_t;
   /* File get current position method.*/                                    \
   fileoffset_t (*getposition)(void *instance);                              \
   /* File seek method.*/                                                    \
-  fileoffset_t (*lseek)(void *instance, fileoffset_t offset);
+  uint32_t (*lseek)(void *instance, fileoffset_t offset);
 
 /**
  * @brief   @p BaseFileStream specific data.
@@ -110,6 +115,9 @@ typedef struct {
  * @details The function closes a file stream.
  *
  * @param[in] ip        pointer to a @p BaseFileStream or derived class
+ * @return              The operation status.
+ * @retval FILE_OK      no error.
+ * @retval FILE_ERROR   operation failed.
  *
  * @api
  */
@@ -119,38 +127,44 @@ typedef struct {
  * @brief   Returns an implementation dependent error code.
  *
  * @param[in] ip        pointer to a @p BaseFileStream or derived class
+ * @return              Implementation dependent error code.
  *
  * @api
  */
-#define chFileStreamGetError ((ip)->vmt->geterror(ip))
+#define chFileStreamGetError(ip) ((ip)->vmt->geterror(ip))
 
 /**
  * @brief   Returns the current file size.
  *
  * @param[in] ip        pointer to a @p BaseFileStream or derived class
+ * @return              The file size.
  *
  * @api
  */
-#define chFileStreamGetSize ((ip)->vmt->getposition(ip))
+#define chFileStreamGetSize(ip) ((ip)->vmt->getposition(ip))
 
 /**
  * @brief   Returns the current file pointer position.
  *
  * @param[in] ip        pointer to a @p BaseFileStream or derived class
+ * @return              The current position inside the file.
  *
  * @api
  */
-#define chFileStreamGetPosition ((ip)->vmt->getposition(ip))
+#define chFileStreamGetPosition(ip) ((ip)->vmt->getposition(ip))
 
 /**
  * @brief   Moves the file current pointer to an absolute position.
  *
  * @param[in] ip        pointer to a @p BaseFileStream or derived class
  * @param[in] offset    new absolute position
+ * @return              The operation status.
+ * @retval FILE_OK      no error.
+ * @retval FILE_ERROR   operation failed.
  *
  * @api
  */
-#define chFileStreamSeek ((ip)->vmt->lseek(ip, offset))
+#define chFileStreamSeek(ip) ((ip)->vmt->lseek(ip, offset))
 /** @} */
 
 #endif /* _CHFILES_H_ */