diff --git a/docker/centos-7/Dockerfile b/docker/centos-7/Dockerfile
index 3ca8e493..b7310fb5 100644
--- a/docker/centos-7/Dockerfile
+++ b/docker/centos-7/Dockerfile
@@ -151,7 +151,7 @@ RUN cp /usr/local/lib/libgtest.a /lib64/
 
 # install specific arakoon.
 RUN git clone https://github.com/openvstorage/arakoon.git
-RUN cd arakoon && git pull && git checkout 1.9.20
+RUN cd arakoon && git pull && git checkout 1.9.21
 RUN cd arakoon && eval `${opam_env}` && make
 RUN cd arakoon && eval `${opam_env}` \
     && export PREFIX=${opam_root}/${ocaml_version} \
diff --git a/docker/ubuntu-14.04/Dockerfile b/docker/ubuntu-14.04/Dockerfile
index 2a239737..02332c6e 100644
--- a/docker/ubuntu-14.04/Dockerfile
+++ b/docker/ubuntu-14.04/Dockerfile
@@ -136,7 +136,7 @@ RUN cd /usr/src/gtest \
 
 # install specific arakoon.
 RUN git clone https://github.com/openvstorage/arakoon.git
-RUN cd arakoon && git pull && git checkout 1.9.20
+RUN cd arakoon && git pull && git checkout 1.9.21
 RUN cd arakoon && eval `${opam_env}` && make
 RUN cd arakoon && eval `${opam_env}` \
     && export PREFIX=${opam_root}/${ocaml_version} \
diff --git a/docker/ubuntu-16.04/Dockerfile b/docker/ubuntu-16.04/Dockerfile
index 527daf4b..0917c2d6 100644
--- a/docker/ubuntu-16.04/Dockerfile
+++ b/docker/ubuntu-16.04/Dockerfile
@@ -110,7 +110,7 @@ RUN cd /usr/src/gtest \
 
 # install specific arakoon.
 RUN git clone https://github.com/openvstorage/arakoon.git
-RUN cd arakoon && git pull && git checkout 1.9.20
+RUN cd arakoon && git pull && git checkout 1.9.21
 RUN cd arakoon && eval `${opam_env}` && make
 RUN cd arakoon && eval `${opam_env}` \
     && export PREFIX=${opam_root}/${ocaml_version} \