diff --git a/pkg/spiffs/Makefile.include b/pkg/spiffs/Makefile.include
index 4e77c3a5e2..6d3c0b57b6 100644
--- a/pkg/spiffs/Makefile.include
+++ b/pkg/spiffs/Makefile.include
@@ -4,3 +4,6 @@ INCLUDES += -I$(PKGDIRBASE)/spiffs/src/
 ifneq (,$(filter spiffs_fs,$(USEMODULE)))
   DIRS += $(RIOTBASE)/pkg/spiffs/fs
 endif
+
+SPIFFS_NB_FD ?= 8
+CFLAGS += '-DSPIFFS_FS_FD_SPACE_SIZE=(32 * $(SPIFFS_NB_FD))'