diff --git a/Makefile b/Makefile
index eef5fc7..194cc54 100644
--- a/Makefile
+++ b/Makefile
@@ -26,7 +26,7 @@ EMU_OBJ := $(BUILD_DIR)/emulated.riscv.elf
 EMU_OBJ_LICENSE ?= $(BUILD_DIR)/license
 EMU_OBJ_LICENSE_IF_EXISTS := $(wildcard $(EMU_OBJ_LICENSE))
 
-README_FILE ?= $(BUILD_DIR)/README.md
+README_FILE ?= $(BUILD_DIR)/README.txt
 ZIP_FILE ?= $(BUILD_DIR)/challenge.zip
 ZIP_FILE_IF_EXISTS := $(wildcard $(ZIP_FILE))