diff --git a/lib/srfi/111.sld b/lib/srfi/111.sld
new file mode 100644
index 00000000..8497f0f4
--- /dev/null
+++ b/lib/srfi/111.sld
@@ -0,0 +1,8 @@
+(define-library (srfi 111)
+  (import (scheme base))
+  (export box box? unbox set-box!)
+  (begin
+    (define-record-type Box
+      (box value)
+      box?
+      (value unbox set-box!))))