diff --git a/src/default/spiffs_config.h b/src/default/spiffs_config.h
index 5a55921..65667fc 100644
--- a/src/default/spiffs_config.h
+++ b/src/default/spiffs_config.h
@@ -169,6 +169,15 @@
 #define SPIFFS_HAL_CALLBACK_EXTRA         0
 #endif
 
+// Enable this if you want to add an integer offset to all file handles
+// (spiffs_file). This is useful if running multiple instances of spiffs on
+// same target, in order to recognise to what spiffs instance a file handle
+// belongs.
+// NB: This adds config field fh_ix_offset in the configuration struct when
+// mounting, which must be defined.
+#ifndef SPIFFS_FILEHDL_OFFSET
+#define SPIFFS_FILEHDL_OFFSET                 0
+#endif
 
 // Set SPIFFS_TEST_VISUALISATION to non-zero to enable SPIFFS_vis function
 // in the api. This function will visualize all filesystem using given printf
diff --git a/src/spiffs.h b/src/spiffs.h
index 4a0b147..2912f59 100644
--- a/src/spiffs.h
+++ b/src/spiffs.h
@@ -186,6 +186,11 @@ typedef struct {
   // logical size of a page, must be at least
   // log_block_size / 8
   u32_t log_page_size;
+
+#endif
+#if SPIFFS_FILEHDL_OFFSET
+  // an integer offset added to each file handle
+  u16_t fh_ix_offset;
 #endif
 } spiffs_config;
 
diff --git a/src/spiffs_hydrogen.c b/src/spiffs_hydrogen.c
index 6763ac5..5daa28d 100644
--- a/src/spiffs_hydrogen.c
+++ b/src/spiffs_hydrogen.c
@@ -8,6 +8,14 @@
 #include "spiffs.h"
 #include "spiffs_nucleus.h"
 
+#if SPIFFS_FILEHDL_OFFSET
+#define SPIFFS_FH_OFFS(fs, fh)   ((fh) != 0 ? ((fh) + (fs)->cfg.fh_ix_offset) : 0)
+#define SPIFFS_FH_UNOFFS(fs, fh) ((fh) != 0 ? ((fh) - (fs)->cfg.fh_ix_offset) : 0)
+#else
+#define SPIFFS_FH_OFFS(fs, fh)   (fh)
+#define SPIFFS_FH_UNOFFS(fs, fh) (fh)
+#endif
+
 #if SPIFFS_CACHE == 1
 static s32_t spiffs_fflush_cache(spiffs *fs, spiffs_file fh);
 #endif
@@ -236,7 +244,7 @@ spiffs_file SPIFFS_open(spiffs *fs, char *path, spiffs_flags flags, spiffs_mode
 
   SPIFFS_UNLOCK(fs);
 
-  return fd->file_nbr;
+  return SPIFFS_FH_OFFS(fs, fd->file_nbr);
 }
 
 spiffs_file SPIFFS_open_by_dirent(spiffs *fs, struct spiffs_dirent *e, spiffs_flags flags, spiffs_mode mode) {
@@ -266,7 +274,7 @@ spiffs_file SPIFFS_open_by_dirent(spiffs *fs, struct spiffs_dirent *e, spiffs_fl
 
   SPIFFS_UNLOCK(fs);
 
-  return fd->file_nbr;
+  return SPIFFS_FH_OFFS(fs, fd->file_nbr);
 }
 
 s32_t SPIFFS_read(spiffs *fs, spiffs_file fh, void *buf, s32_t len) {
@@ -277,6 +285,7 @@ s32_t SPIFFS_read(spiffs *fs, spiffs_file fh, void *buf, s32_t len) {
   spiffs_fd *fd;
   s32_t res;
 
+  fh = SPIFFS_FH_UNOFFS(fs, fh);
   res = spiffs_fd_get(fs, fh, &fd);
   SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
 
@@ -353,6 +362,7 @@ s32_t SPIFFS_write(spiffs *fs, spiffs_file fh, void *buf, s32_t len) {
   s32_t res;
   u32_t offset;
 
+  fh = SPIFFS_FH_UNOFFS(fs, fh);
   res = spiffs_fd_get(fs, fh, &fd);
   SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
 
@@ -470,6 +480,7 @@ s32_t SPIFFS_lseek(spiffs *fs, spiffs_file fh, s32_t offs, int whence) {
 
   spiffs_fd *fd;
   s32_t res;
+  fh = SPIFFS_FH_UNOFFS(fs, fh);
   res = spiffs_fd_get(fs, fh, &fd);
   SPIFFS_API_CHECK_RES(fs, res);
 
@@ -549,6 +560,7 @@ s32_t SPIFFS_fremove(spiffs *fs, spiffs_file fh) {
 
   spiffs_fd *fd;
   s32_t res;
+  fh = SPIFFS_FH_UNOFFS(fs, fh);
   res = spiffs_fd_get(fs, fh, &fd);
   SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
 
@@ -618,6 +630,7 @@ s32_t SPIFFS_fstat(spiffs *fs, spiffs_file fh, spiffs_stat *s) {
   spiffs_fd *fd;
   s32_t res;
 
+  fh = SPIFFS_FH_UNOFFS(fs, fh);
   res = spiffs_fd_get(fs, fh, &fd);
   SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
 
@@ -675,6 +688,7 @@ s32_t SPIFFS_fflush(spiffs *fs, spiffs_file fh) {
   s32_t res = SPIFFS_OK;
 #if SPIFFS_CACHE_WR
   SPIFFS_LOCK(fs);
+  fh = SPIFFS_FH_UNOFFS(fs, fh);
   res = spiffs_fflush_cache(fs, fh);
   SPIFFS_API_CHECK_RES_UNLOCK(fs,res);
   SPIFFS_UNLOCK(fs);
@@ -690,6 +704,7 @@ s32_t SPIFFS_close(spiffs *fs, spiffs_file fh) {
   s32_t res = SPIFFS_OK;
   SPIFFS_LOCK(fs);
 
+  fh = SPIFFS_FH_UNOFFS(fs, fh);
 #if SPIFFS_CACHE
   res = spiffs_fflush_cache(fs, fh);
   SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
diff --git a/src/test/params_test.h b/src/test/params_test.h
index 95dfd36..bb5f52d 100644
--- a/src/test/params_test.h
+++ b/src/test/params_test.h
@@ -43,6 +43,11 @@ typedef unsigned char u8_t;
 #define SPIFFS_HAL_CALLBACK_EXTRA       1
 #endif
 
+#define SPIFFS_FILEHDL_OFFSET           1
+#if SPIFFS_FILEHDL_OFFSET
+#define TEST_SPIFFS_FILEHDL_OFFSET      0x1000
+#endif
+
 // Enable/disable
 
 void real_assert(int c, const char *n, const char *file, int l);
diff --git a/src/test/test_bugreports.c b/src/test/test_bugreports.c
index d24f25a..2c78f44 100644
--- a/src/test/test_bugreports.c
+++ b/src/test/test_bugreports.c
@@ -388,7 +388,12 @@ TEST(truncate_48) {
   TEST_CHECK_GE(fd, 0);
 
   spiffs_fd *desc;
+#if SPIFFS_FILEHDL_OFFSET
+  res = spiffs_fd_get(FS, fd - TEST_SPIFFS_FILEHDL_OFFSET, &desc);
+#else
   res = spiffs_fd_get(FS, fd, &desc);
+#endif
+
   TEST_CHECK_GE(res, 0);
 
   TEST_CHECK_EQ(desc->size, len);
diff --git a/src/test/test_hydrogen.c b/src/test/test_hydrogen.c
index 795e451..539e123 100644
--- a/src/test/test_hydrogen.c
+++ b/src/test/test_hydrogen.c
@@ -225,6 +225,42 @@ TEST(file_by_open_excl)
 }
 TEST_END(file_by_open_excl)
 
+#if SPIFFS_FILEHDL_OFFSET
+TEST(open_fh_offs)
+{
+  int res;
+  spiffs_stat s;
+  spiffs_file fd1, fd2, fd3;
+  fd1 = SPIFFS_open(FS, "1", SPIFFS_CREAT | SPIFFS_EXCL, 0);
+  fd2 = SPIFFS_open(FS, "2", SPIFFS_CREAT | SPIFFS_EXCL, 0);
+  fd3 = SPIFFS_open(FS, "3", SPIFFS_CREAT | SPIFFS_EXCL, 0);
+  TEST_CHECK(fd1 >= TEST_SPIFFS_FILEHDL_OFFSET);
+  TEST_CHECK(fd2 >= TEST_SPIFFS_FILEHDL_OFFSET);
+  TEST_CHECK(fd3 >= TEST_SPIFFS_FILEHDL_OFFSET);
+  SPIFFS_close(FS, fd1);
+  fd1 = SPIFFS_open(FS, "2", SPIFFS_RDONLY, 0);
+  TEST_CHECK(fd1 >= TEST_SPIFFS_FILEHDL_OFFSET);
+  SPIFFS_close(FS, fd2);
+  fd2 = SPIFFS_open(FS, "3", SPIFFS_RDONLY, 0);
+  TEST_CHECK(fd2 >= TEST_SPIFFS_FILEHDL_OFFSET);
+  SPIFFS_close(FS, fd3);
+  fd3 = SPIFFS_open(FS, "1", SPIFFS_RDONLY, 0);
+  TEST_CHECK(fd3 >= TEST_SPIFFS_FILEHDL_OFFSET);
+  SPIFFS_close(FS, fd1);
+  SPIFFS_close(FS, fd2);
+  SPIFFS_close(FS, fd3);
+  fd1 = SPIFFS_open(FS, "3", SPIFFS_RDONLY, 0);
+  TEST_CHECK(fd1 >= TEST_SPIFFS_FILEHDL_OFFSET);
+  SPIFFS_close(FS, fd1);
+  fd1 = SPIFFS_open(FS, "foo", SPIFFS_RDONLY, 0);
+  TEST_CHECK(fd1 < TEST_SPIFFS_FILEHDL_OFFSET);
+
+  return TEST_RES_OK;
+}
+TEST_END(open_fh_offs)
+
+#endif //SPIFFS_FILEHDL_OFFSET
+
 TEST(list_dir)
 {
   int res;
diff --git a/src/test/test_spiffs.c b/src/test/test_spiffs.c
index 726aa9e..07d46ee 100644
--- a/src/test/test_spiffs.c
+++ b/src/test/test_spiffs.c
@@ -332,7 +332,9 @@ s32_t fs_mount_specific(u32_t phys_addr, u32_t phys_size,
   c.phys_addr = phys_addr;
   c.phys_erase_block = phys_sector_size;
   c.phys_size = phys_size;
-
+#if SPIFFS_FILEHDL_OFFSET
+  c.fh_ix_offset = TEST_SPIFFS_FILEHDL_OFFSET;
+#endif
   return SPIFFS_mount(&__fs, &c, _work, _fds, sizeof(_fds), _cache, sizeof(_cache), spiffs_check_cb_f);
 }