diff --git a/1.9/Dockerfile b/1.9/Dockerfile
index 33d84393d..ff5ccf98c 100644
--- a/1.9/Dockerfile
+++ b/1.9/Dockerfile
@@ -15,8 +15,7 @@ RUN apt-get update \
 	&& autoconf \
 	&& ./configure --disable-install-doc \
 	&& make \
-	&& apt-get purge -y bison ruby procps \
-	&& apt-get autoremove -y \
+	&& apt-get purge -y --auto-remove bison ruby procps \
 	&& make install \
 	&& rm -r /usr/src/ruby
 
diff --git a/2.1/Dockerfile b/2.1/Dockerfile
index ead02c37e..a0b996c83 100644
--- a/2.1/Dockerfile
+++ b/2.1/Dockerfile
@@ -15,8 +15,7 @@ RUN apt-get update \
 	&& autoconf \
 	&& ./configure --disable-install-doc \
 	&& make -j"$(nproc)" \
-	&& apt-get purge -y bison ruby procps \
-	&& apt-get autoremove -y \
+	&& apt-get purge -y --auto-remove bison ruby procps \
 	&& make install \
 	&& rm -r /usr/src/ruby