diff --git a/6.0/Dockerfile b/6.0/Dockerfile
index 502c76b..55bdf16 100644
--- a/6.0/Dockerfile
+++ b/6.0/Dockerfile
@@ -21,14 +21,14 @@ RUN docker-php-ext-configure gd --with-png-dir=/usr --with-jpeg-dir=/usr \
 
 # set recommended PHP.ini settings
 # see https://secure.php.net/manual/en/opcache.installation.php
-RUN ( \
-    echo "opcache.memory_consumption=128"; \
-    echo "opcache.interned_strings_buffer=8"; \
-    echo "opcache.max_accelerated_files=4000"; \
-    echo "opcache.revalidate_freq=60"; \
-    echo "opcache.fast_shutdown=1"; \
-    echo "opcache.enable_cli=1"; \
-    ) > /usr/local/etc/php/conf.d/opcache-recommended.ini
+RUN { \
+		echo 'opcache.memory_consumption=128'; \
+		echo 'opcache.interned_strings_buffer=8'; \
+		echo 'opcache.max_accelerated_files=4000'; \
+		echo 'opcache.revalidate_freq=60'; \
+		echo 'opcache.fast_shutdown=1'; \
+		echo 'opcache.enable_cli=1'; \
+	} > /usr/local/etc/php/conf.d/opcache-recommended.ini
 
 RUN a2enmod rewrite
 
diff --git a/7.0/Dockerfile b/7.0/Dockerfile
index bf69b5e..dd109c9 100644
--- a/7.0/Dockerfile
+++ b/7.0/Dockerfile
@@ -21,14 +21,14 @@ RUN docker-php-ext-configure gd --with-png-dir=/usr --with-jpeg-dir=/usr \
 
 # set recommended PHP.ini settings
 # see https://secure.php.net/manual/en/opcache.installation.php
-RUN ( \
-    echo "opcache.memory_consumption=128"; \
-    echo "opcache.interned_strings_buffer=8"; \
-    echo "opcache.max_accelerated_files=4000"; \
-    echo "opcache.revalidate_freq=60"; \
-    echo "opcache.fast_shutdown=1"; \
-    echo "opcache.enable_cli=1"; \
-    ) > /usr/local/etc/php/conf.d/opcache-recommended.ini
+RUN { \
+		echo 'opcache.memory_consumption=128'; \
+		echo 'opcache.interned_strings_buffer=8'; \
+		echo 'opcache.max_accelerated_files=4000'; \
+		echo 'opcache.revalidate_freq=60'; \
+		echo 'opcache.fast_shutdown=1'; \
+		echo 'opcache.enable_cli=1'; \
+	} > /usr/local/etc/php/conf.d/opcache-recommended.ini
 
 RUN a2enmod rewrite
 
diff --git a/8.0/Dockerfile b/8.0/Dockerfile
index 62db79f..c5c2089 100644
--- a/8.0/Dockerfile
+++ b/8.0/Dockerfile
@@ -21,14 +21,14 @@ RUN docker-php-ext-configure gd --with-png-dir=/usr --with-jpeg-dir=/usr \
 
 # set recommended PHP.ini settings
 # see https://secure.php.net/manual/en/opcache.installation.php
-RUN ( \
-    echo "opcache.memory_consumption=128"; \
-    echo "opcache.interned_strings_buffer=8"; \
-    echo "opcache.max_accelerated_files=4000"; \
-    echo "opcache.revalidate_freq=60"; \
-    echo "opcache.fast_shutdown=1"; \
-    echo "opcache.enable_cli=1"; \
-    ) > /usr/local/etc/php/conf.d/opcache-recommended.ini
+RUN { \
+		echo 'opcache.memory_consumption=128'; \
+		echo 'opcache.interned_strings_buffer=8'; \
+		echo 'opcache.max_accelerated_files=4000'; \
+		echo 'opcache.revalidate_freq=60'; \
+		echo 'opcache.fast_shutdown=1'; \
+		echo 'opcache.enable_cli=1'; \
+	} > /usr/local/etc/php/conf.d/opcache-recommended.ini
 
 # PECL extensions
 RUN pecl install APCu-beta \
diff --git a/8.1/Dockerfile b/8.1/Dockerfile
index cdc75c8..5c24276 100644
--- a/8.1/Dockerfile
+++ b/8.1/Dockerfile
@@ -22,14 +22,14 @@ RUN docker-php-ext-configure gd --with-png-dir=/usr --with-jpeg-dir=/usr \
 
 # set recommended PHP.ini settings
 # see https://secure.php.net/manual/en/opcache.installation.php
-RUN ( \
-    echo "opcache.memory_consumption=128"; \
-    echo "opcache.interned_strings_buffer=8"; \
-    echo "opcache.max_accelerated_files=4000"; \
-    echo "opcache.revalidate_freq=60"; \
-    echo "opcache.fast_shutdown=1"; \
-    echo "opcache.enable_cli=1"; \
-    ) > /usr/local/etc/php/conf.d/opcache-recommended.ini
+RUN { \
+		echo 'opcache.memory_consumption=128'; \
+		echo 'opcache.interned_strings_buffer=8'; \
+		echo 'opcache.max_accelerated_files=4000'; \
+		echo 'opcache.revalidate_freq=60'; \
+		echo 'opcache.fast_shutdown=1'; \
+		echo 'opcache.enable_cli=1'; \
+	} > /usr/local/etc/php/conf.d/opcache-recommended.ini
 
 # PECL extensions
 RUN pecl install APCu-beta redis memcached \