diff --git a/Makefile.cfg b/Makefile.cfg
index e3028c6..c787a7c 100644
--- a/Makefile.cfg
+++ b/Makefile.cfg
@@ -20,7 +20,7 @@ RM = rm -f
 AS = sh3eb-elf-as
 ## C compiler
 CC = sh3eb-elf-gcc
-CFLAGS = -m3 -mb -Os -nostdlib -Wall -Wextra -Wno-main -pedantic -std=c11 -I $(INCDIR)
+CFLAGS = -m3 -mb -O0 -nostdlib -Wall -Wextra -Wno-main -pedantic -std=c11 -I $(INCDIR)
 ## Linker
 LD = sh3eb-elf-gcc
 LFLAGS = -nostdlib -T $(SCPTDIR)/addin.ld -L $(LIBDIR) $(addprefix -l,$(LIB))