diff --git a/test/Dockerfile-bash4-0 b/test/Dockerfile-bash4-0
index f732258..8147eca 100644
--- a/test/Dockerfile-bash4-0
+++ b/test/Dockerfile-bash4-0
@@ -31,4 +31,4 @@ RUN /bats-core/install.sh /usr/local
 
 # Use supervisord to run nginx in the background
 COPY ./test/test-config/alpine-supervisord.conf /etc/supervisord.conf
-CMD tail -f /dev/null
+CMD [ "tail", "-f", "/dev/null" ]
diff --git a/test/Dockerfile-bash4-2 b/test/Dockerfile-bash4-2
index 795ee61..90b6948 100644
--- a/test/Dockerfile-bash4-2
+++ b/test/Dockerfile-bash4-2
@@ -31,4 +31,4 @@ RUN /bats-core/install.sh /usr/local
 
 # Use supervisord to run nginx in the background
 COPY ./test/test-config/alpine-supervisord.conf /etc/supervisord.conf
-CMD tail -f /dev/null
+CMD [ "tail", "-f", "/dev/null" ]
diff --git a/test/Dockerfile-bash5-0 b/test/Dockerfile-bash5-0
index 128e615..27e6453 100644
--- a/test/Dockerfile-bash5-0
+++ b/test/Dockerfile-bash5-0
@@ -31,4 +31,4 @@ RUN /bats-core/install.sh /usr/local
 
 # Use supervisord to run nginx in the background
 COPY ./test/test-config/alpine-supervisord.conf /etc/supervisord.conf
-CMD tail -f /dev/null
+CMD [ "tail", "-f", "/dev/null" ]
diff --git a/test/Dockerfile-centos7-dynu b/test/Dockerfile-centos7-dynu
index 074a0a2..46a413f 100644
--- a/test/Dockerfile-centos7-dynu
+++ b/test/Dockerfile-centos7-dynu
@@ -30,4 +30,4 @@ RUN /bats-core/install.sh /usr/local
 EXPOSE 80 443
 
 # Run eternal loop - for testing
-CMD tail -f /dev/null
+CMD [ "tail", "-f", "/dev/null" ]
diff --git a/test/Dockerfile-ubuntu-acmedns b/test/Dockerfile-ubuntu-acmedns
index db0320a..55241a8 100644
--- a/test/Dockerfile-ubuntu-acmedns
+++ b/test/Dockerfile-ubuntu-acmedns
@@ -36,4 +36,4 @@ RUN git clone https://github.com/bats-core/bats-assert /bats-assert
 RUN /bats-core/install.sh /usr/local
 
 # Run eternal loop - for testing
-CMD tail -f /dev/null
+CMD [ "tail", "-f", "/dev/null" ]
diff --git a/test/Dockerfile-ubuntu-dynu b/test/Dockerfile-ubuntu-dynu
index 8f655b5..d2a42cd 100644
--- a/test/Dockerfile-ubuntu-dynu
+++ b/test/Dockerfile-ubuntu-dynu
@@ -33,4 +33,4 @@ RUN git clone https://github.com/bats-core/bats-assert /bats-assert
 RUN /bats-core/install.sh /usr/local
 
 # Run eternal loop - for testing
-CMD tail -f /dev/null
+CMD [ "tail", "-f", "/dev/null" ]