diff --git a/README.md b/README.md
index d083a1d..3213594 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,8 @@ Inspired by xv6
 For a quick reference on RISC-V assembly:
 - https://risc-v.guru/instructions/
 
+Some low-level string format routines borrowed from [mini-printf](https://github.com/mludvig/mini-printf)
+
 Toolchains:
 - https://github.com/xpack-dev-tools/riscv-none-elf-gcc-xpack
 - https://github.com/xpack-dev-tools/qemu-riscv-xpack/