diff --git a/fs/exfat/Make.defs b/fs/exfat/Make.defs
index 6f09d986071..7fd58770ccd 100644
--- a/fs/exfat/Make.defs
+++ b/fs/exfat/Make.defs
@@ -41,7 +41,7 @@ VPATH += : exfat/exfat/mkfs
 CFLAGS += ${shell $(INCDIR) $(INCDIROPT) "$(CC)" exfat/exfat/libexfat}
 CFLAGS += ${shell $(INCDIR) $(INCDIROPT) "$(CC)" exfat/exfat/mkfs}
 CFLAGS += ${shell $(INCDIR) $(INCDIROPT) "$(CC)" exfat/}
-CFLAGS += -D__GLIBC__
+CFLAGS += -D__GLIBC__ -DEXFAT_UTF8_NAME_BUFFER_MAX=EXFAT_NAME_MAX
 
 EXFAT_VERSION ?= 1.3.0
 EXFAT_TARBALL = v$(EXFAT_VERSION).tar.gz