diff --git a/Dockerfile b/Dockerfile
index a957dc8..c3488e8 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -4,9 +4,9 @@
 FROM ubuntu as opfsbuilder
 WORKDIR /root/
 RUN apt-get update \
- && apt-get install -y git build-essential \
- && git clone https://github.com/titech-os/opfs.git \
- && (cd opfs; make PREFIX=/root/local install)
+     && apt-get install -y git build-essential \
+     && git clone https://github.com/titech-os/opfs.git \
+     && (cd opfs; make PREFIX=/root/local install)
 
 FROM ubuntu
 
@@ -22,26 +22,27 @@ ENV XV6=${HOME}/xv6-riscv
 COPY --from=opfsbuilder /root/local/bin/* /usr/local/bin/
 
 RUN apt-get update \
- && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends tzdata \
- && ln -sf /usr/share/zoneinfo/${TZ} /etc/localtime \
- && dpkg-reconfigure --frontend noninteractive tzdata \
- && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
-      sudo \
-      git \
-      build-essential \
-      gdb-multiarch \
-      qemu-system-misc \
-      gcc-riscv64-unknown-elf \
-      binutils-riscv64-unknown-elf \
- && rm -rf /var/lib/apt/lists/* \
- && groupadd ${GROUP} \
- && useradd -g ${GROUP} -m ${USER} \
- && (echo "${USER}:${PASS}" | chpasswd) \
- && gpasswd -a ${USER} sudo \
- && mkdir -p ${XV6} \
- && chown -R ${USER}:${GROUP} ${XV6} \
- && (echo "add-auto-load-safe-path ${XV6}/.gdbinit" > ${HOME}/.gdbinit) \
- && chown ${USER}:${GROUP} ${HOME}/.gdbinit
+     && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends tzdata \
+     && ln -sf /usr/share/zoneinfo/${TZ} /etc/localtime \
+     && dpkg-reconfigure --frontend noninteractive tzdata \
+     && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
+     sudo \
+     git \
+     build-essential \
+     gdb-multiarch \
+     qemu-system-misc \
+     gcc-riscv64-unknown-elf \
+     binutils-riscv64-unknown-elf \
+     valgrind \
+     && rm -rf /var/lib/apt/lists/* \
+     && groupadd ${GROUP} \
+     && useradd -g ${GROUP} -m ${USER} \
+     && (echo "${USER}:${PASS}" | chpasswd) \
+     && gpasswd -a ${USER} sudo \
+     && mkdir -p ${XV6} \
+     && chown -R ${USER}:${GROUP} ${XV6} \
+     && (echo "add-auto-load-safe-path ${XV6}/.gdbinit" > ${HOME}/.gdbinit) \
+     && chown ${USER}:${GROUP} ${HOME}/.gdbinit
 
 USER ${USER}
 WORKDIR ${XV6}