diff --git a/file.c b/file.c
index d204b35c36..62f954ac40 100644
--- a/file.c
+++ b/file.c
@@ -81,9 +81,9 @@ typedef struct statvfs statfs_t;
 #ifndef WITHOUT_STATFS
 static VALUE rb_statfs_new(const statfs_t *st);
 #if defined(HAVE_FSTATFS)
-#define FSTATFS(f, s) Fstatfs((f), (s))
+#define FSTATFS(f, s) fstatfs((f), (s))
 #elif !defined(HAVE_FSTATVFS)
-#define FSTATFS(f, s) Fstatvfs((f), (s))
+#define FSTATFS(f, s) fstatvfs((f), (s))
 #endif
 #endif