diff --git a/os/vfs/include/vfsparser.h b/os/vfs/include/vfsparser.h
index 0ed2b8235..023748bb0 100644
--- a/os/vfs/include/vfsparser.h
+++ b/os/vfs/include/vfsparser.h
@@ -58,7 +58,7 @@ extern "C" {
   msg_t vfs_parse_match_separator(const char **pathp);
   msg_t vfs_parse_match_end(const char **pathp);
   msg_t vfs_parse_get_fname(const char **pathp, char *fname);
-  msg_t vfs_parse_copy_with_separator(char *dst, const char *src);
+  size_t vfs_parse_copy_with_separator(char *dst, const char *src);
 #ifdef __cplusplus
 }
 #endif
diff --git a/os/vfs/src/vfsparser.c b/os/vfs/src/vfsparser.c
index 3d93517d2..c83c58253 100644
--- a/os/vfs/src/vfsparser.c
+++ b/os/vfs/src/vfsparser.c
@@ -136,7 +136,18 @@ msg_t vfs_parse_get_fname(const char **pathp, char *fname) {
   }
 }
 
-msg_t vfs_parse_copy_with_separator(char *dst, const char *src) {
+/**
+ * @brief   Copies a path into a destination buffer.
+ * @details Up to @p VFS_CFG_PATHLEN_MAX characters are copied. A path
+ *          separator is added to the end of the path if not present.
+ *
+ * @param[out] dst              The destination buffer.
+ * @param[in] src               The source path.
+ * @return                      The copied path size not including the final
+ *                              zero.
+ * @retval 0                    If the path size exceeded @p VFS_CFG_PATHLEN_MAX.
+ */
+size_t vfs_parse_copy_with_separator(char *dst, const char *src) {
   size_t n = 0U;
   char lc = '\0';
 
@@ -144,7 +155,7 @@ msg_t vfs_parse_copy_with_separator(char *dst, const char *src) {
   while ((*dst = *src) != '\0') {
 
     if (n > VFS_CFG_PATHLEN_MAX) {
-      return VFS_RET_ENAMETOOLONG;
+      return 0U;
     }
 
     lc = *src++;
@@ -156,7 +167,7 @@ msg_t vfs_parse_copy_with_separator(char *dst, const char *src) {
   if (lc != '/') {
 
     if (n > VFS_CFG_PATHLEN_MAX) {
-      return VFS_RET_ENAMETOOLONG;
+      return 0U;
     }
 
     *dst++ = '/';
@@ -164,7 +175,7 @@ msg_t vfs_parse_copy_with_separator(char *dst, const char *src) {
     n++;
   }
 
-  return (msg_t)n;
+  return n;
 }
 
 /** @} */