diff --git a/gnu/usr.bin/cc50/libbackend/Makefile b/gnu/usr.bin/cc50/libbackend/Makefile
index 901655f..da508c7 100644
--- a/gnu/usr.bin/cc50/libbackend/Makefile
+++ b/gnu/usr.bin/cc50/libbackend/Makefile
@@ -361,7 +361,7 @@ SRCS=	wide-int.cc wide-int-print.cc
 # hack to force c++ compiler to compile *.c files to create library
 .for cfile in ${BACKEND_OBJS}
 ${cfile}: ${cfile:.o=.c}
-	${CXX} ${STATIC_CXXFLAGS} ${CXXFLAGS} -c ${.IMPSRC} -o ${.TARGET}
+	${CXX} ${STATIC_CXXFLAGS} ${CXXFLAGS} -c ${.IMPSRC} -o ${.TARGET} -O0
 .endfor
 
 dfp.o: gstdint.h