diff --git a/hw/application_fpga/Makefile b/hw/application_fpga/Makefile
index 7fc78d0..1e524ff 100644
--- a/hw/application_fpga/Makefile
+++ b/hw/application_fpga/Makefile
@@ -38,7 +38,7 @@ OBJCOPY ?= llvm-objcopy
 CC = clang
 
 CFLAGS = -target riscv32-unknown-none-elf -march=rv32iczmmul -mabi=ilp32 \
-   -static -std=gnu99 -O2 -ffast-math -fno-common -fno-builtin-printf \
+   -static -std=gnu99 -Os -ffast-math -fno-common -fno-builtin-printf \
    -fno-builtin-putchar -fno-builtin-memcpy -nostdlib -mno-relax -Wall \
    -Wpedantic -Wno-language-extension-token -flto -g -DNOCONSOLE