diff --git a/test/Dockerfile-bash4-0 b/test/Dockerfile-bash4-0
index 6642ae4..f732258 100644
--- a/test/Dockerfile-bash4-0
+++ b/test/Dockerfile-bash4-0
@@ -20,7 +20,7 @@ RUN adduser -D ftpuser
 RUN echo 'ftpuser:ftpuser' | chpasswd
 RUN adduser ftpuser www-data
 RUN adduser root www-data
-RUN chown -R ftpuser.www-data /var/www
+RUN chown -R ftpuser:www-data /var/www
 RUN chmod g+w -R /var/www
 
 # BATS (Bash Automated Testings)
diff --git a/test/Dockerfile-bash4-2 b/test/Dockerfile-bash4-2
index 3ad5961..795ee61 100644
--- a/test/Dockerfile-bash4-2
+++ b/test/Dockerfile-bash4-2
@@ -20,7 +20,7 @@ RUN adduser -D ftpuser
 RUN echo 'ftpuser:ftpuser' | chpasswd
 RUN adduser ftpuser www-data
 RUN adduser root www-data
-RUN chown -R ftpuser.www-data /var/www
+RUN chown -R ftpuser:www-data /var/www
 RUN chmod g+w -R /var/www
 
 # BATS (Bash Automated Testings)
diff --git a/test/Dockerfile-bash5-0 b/test/Dockerfile-bash5-0
index dca5eb3..128e615 100644
--- a/test/Dockerfile-bash5-0
+++ b/test/Dockerfile-bash5-0
@@ -20,7 +20,7 @@ RUN adduser -D ftpuser
 RUN echo 'ftpuser:ftpuser' | chpasswd
 RUN adduser ftpuser www-data
 RUN adduser root www-data
-RUN chown -R ftpuser.www-data /var/www
+RUN chown -R ftpuser:www-data /var/www
 RUN chmod g+w -R /var/www
 
 # BATS (Bash Automated Testings)