diff --git a/Sming/Services/SpifFS/spiffs_sming.c b/Sming/Services/SpifFS/spiffs_sming.c
index 4af5d71998..c7186e127f 100644
--- a/Sming/Services/SpifFS/spiffs_sming.c
+++ b/Sming/Services/SpifFS/spiffs_sming.c
@@ -56,25 +56,31 @@ bool spiffs_format_internal(spiffs_config *cfg)
 {
   if (cfg->phys_addr == 0)
   {
-	SYSTEM_ERROR("Can't format file system, wrong address");
+	SYSTEM_ERROR("Can't format file system, wrong address given.");
+	return false;
+  }
+
+  if (cfg->phys_size == 0)
+  {
+	SYSTEM_ERROR("Can't format file system, wrong size given.");
 	return false;
   }
 
   u32_t sect_first, sect_last;
   sect_first = cfg->phys_addr;
   sect_first = flashmem_get_sector_of_address(sect_first);
-  sect_last = cfg->phys_addr + cfg->phys_size;
+  sect_last = cfg->phys_addr + cfg->phys_size - 1;
   sect_last = flashmem_get_sector_of_address(sect_last);
   debugf("sect_first: %x, sect_last: %x\n", sect_first, sect_last);
   ETS_INTR_LOCK();
-  int total = sect_last - sect_first;
+  int total = sect_last - sect_first + 1;
   int cur = 0;
   int last = -1;
   while( sect_first <= sect_last )
   {
 	if(flashmem_erase_sector( sect_first++ ))
 	{
-		int percent = cur++ * 100 / total;
+		int percent = ++cur * 100 / total;
 		if (percent > last)
 			debugf("%d%%", percent);
 		last = percent;
@@ -85,7 +91,7 @@ bool spiffs_format_internal(spiffs_config *cfg)
 		return false;
 	}
   }
-  debugf("formated");
+  debugf("formatted");
   ETS_INTR_UNLOCK();
 
   return true;
diff --git a/Sming/appspecific/rboot/overrides.c b/Sming/appspecific/rboot/overrides.c
index fcf3d83333..d0b452fe61 100644
--- a/Sming/appspecific/rboot/overrides.c
+++ b/Sming/appspecific/rboot/overrides.c
@@ -8,6 +8,8 @@
 spiffs_config spiffs_get_storage_config()
 {
   spiffs_config cfg = {0};
+  u32_t max_allowed_sector, requested_sector;
+
 #ifdef RBOOT_SPIFFS_0
   cfg.phys_addr = RBOOT_SPIFFS_0;
 #elif RBOOT_SPIFFS_1
@@ -15,7 +17,17 @@ spiffs_config spiffs_get_storage_config()
 #else
 #error "Define either RBOOT_SPIFFS_0 or RBOOT_SPIFFS_1"
 #endif
-  cfg.phys_size = SPIFF_SIZE;
+
+  cfg.phys_addr &= 0xFFFFF000; // get the start address of the sector
+
+  max_allowed_sector = flashmem_get_sector_of_address(INTERNAL_FLASH_SIZE - 1);
+  requested_sector  = flashmem_get_sector_of_address((cfg.phys_addr + SPIFF_SIZE) - 1);
+  if(requested_sector > max_allowed_sector) {
+      debug_w("The requested SPIFFS size is too big.");
+      requested_sector = max_allowed_sector;
+  }
+  cfg.phys_size = ((requested_sector + 1) * INTERNAL_FLASH_SECTOR_SIZE) -  ( ( u32_t )cfg.phys_addr); // get the max size until the sector end.
+
   cfg.phys_erase_block = INTERNAL_FLASH_SECTOR_SIZE; // according to datasheet
   cfg.log_block_size = INTERNAL_FLASH_SECTOR_SIZE * 2; // Important to make large
   cfg.log_page_size = LOG_PAGE_SIZE; // as we said