diff --git a/php-fpm/Dockerfile b/php-fpm/Dockerfile
index 9ee8460..4642024 100644
--- a/php-fpm/Dockerfile
+++ b/php-fpm/Dockerfile
@@ -1078,10 +1078,14 @@ USER root
 ARG INSTALL_PHPDECIMAL=false
 
 RUN if [ ${INSTALL_PHPDECIMAL} = true ]; then \
-    apt-get update -yqq \
-    && apt-get install -y libmpdec-dev \
-    && pecl install decimal \
-    && docker-php-ext-enable decimal \
+    if [ $(php -r "echo PHP_MAJOR_VERSION;") = "5" ]; then \
+      echo 'decimal not support PHP 5.6'; \
+    else \
+      apt-get install -yqq libmpdec-dev \
+      && pecl install decimal \
+      && docker-php-ext-enable decimal \
+      && php -m | grep -q 'decimal' \
+    ;fi \
 ;fi
 
 ###########################################################################
diff --git a/workspace/Dockerfile b/workspace/Dockerfile
index 7ef997b..85fd25d 100644
--- a/workspace/Dockerfile
+++ b/workspace/Dockerfile
@@ -1588,12 +1588,15 @@ USER root
 ARG INSTALL_PHPDECIMAL=false
 
 RUN if [ ${INSTALL_PHPDECIMAL} = true ]; then \
-    apt-get update -yqq \
-    && apt-get install -y libmpdec-dev \
-    && pecl install decimal \
-    && echo "extension=decimal.so" >> /etc/php/${LARADOCK_PHP_VERSION}/mods-available/decimal.ini \
-    && ln -s /etc/php/${LARADOCK_PHP_VERSION}/mods-available/decimal.ini /etc/php/${LARADOCK_PHP_VERSION}/cli/conf.d/30-decimal.ini \
-    && php -m | grep -q 'decimal' \
+    if [ $(php -r "echo PHP_MAJOR_VERSION;") = "5" ]; then \
+      echo 'decimal not support PHP 5.6'; \
+    else \
+      apt-get install -yqq libmpdec-dev \
+      && pecl install decimal \
+      && echo "extension=decimal.so" >> /etc/php/${LARADOCK_PHP_VERSION}/mods-available/decimal.ini \
+      && ln -s /etc/php/${LARADOCK_PHP_VERSION}/mods-available/decimal.ini /etc/php/${LARADOCK_PHP_VERSION}/cli/conf.d/30-decimal.ini \
+      && php -m | grep -q 'decimal' \
+    ;fi \
 ;fi
 
 #