diff --git a/2.3/alpine3.7/Dockerfile b/2.3/alpine3.7/Dockerfile
index f4ea5e884..118f76046 100644
--- a/2.3/alpine3.7/Dockerfile
+++ b/2.3/alpine3.7/Dockerfile
@@ -28,6 +28,7 @@ RUN set -ex \
 		gcc \
 		gdbm-dev \
 		glib-dev \
+		gmp-dev \
 		libc-dev \
 		libffi-dev \
 		libxml2-dev \
diff --git a/2.3/alpine3.8/Dockerfile b/2.3/alpine3.8/Dockerfile
index ebf1b7ca0..59e810506 100644
--- a/2.3/alpine3.8/Dockerfile
+++ b/2.3/alpine3.8/Dockerfile
@@ -28,6 +28,7 @@ RUN set -ex \
 		gcc \
 		gdbm-dev \
 		glib-dev \
+		gmp-dev \
 		libc-dev \
 		libffi-dev \
 		libxml2-dev \
diff --git a/2.3/jessie/slim/Dockerfile b/2.3/jessie/slim/Dockerfile
index 26278a605..6605ade07 100644
--- a/2.3/jessie/slim/Dockerfile
+++ b/2.3/jessie/slim/Dockerfile
@@ -28,7 +28,8 @@ ENV RUBYGEMS_VERSION 3.0.1
 #   we purge system ruby later to make sure our final image uses what we just built
 RUN set -ex \
 	\
-	&& buildDeps=' \
+	&& savedAptMark="$(apt-mark showmanual)" \
+	&& apt-get update && apt-get install -y --no-install-recommends \
 		autoconf \
 		bison \
 		dpkg-dev \
@@ -36,6 +37,7 @@ RUN set -ex \
 		libbz2-dev \
 		libgdbm-dev \
 		libglib2.0-dev \
+		libgmp-dev \
 		libncurses-dev \
 		libreadline-dev \
 		libxml2-dev \
@@ -44,9 +46,6 @@ RUN set -ex \
 		ruby \
 		wget \
 		xz-utils \
-	' \
-	&& apt-get update \
-	&& apt-get install -y --no-install-recommends $buildDeps \
 	&& rm -rf /var/lib/apt/lists/* \
 	\
 	&& wget -O ruby.tar.xz "https://cache.ruby-lang.org/pub/ruby/${RUBY_MAJOR%-rc}/ruby-$RUBY_VERSION.tar.xz" \
@@ -76,10 +75,17 @@ RUN set -ex \
 	&& make -j "$(nproc)" \
 	&& make install \
 	\
-	&& dpkg-query --show --showformat '${package}\n' \
-		| grep -P '^libreadline\d+$' \
-		| xargs apt-mark manual \
-	&& apt-get purge -y --auto-remove $buildDeps \
+	&& apt-mark auto '.*' > /dev/null \
+	&& apt-mark manual $savedAptMark \
+	&& find /usr/local -type f -executable -not \( -name '*tkinter*' \) -exec ldd '{}' ';' \
+		| awk '/=>/ { print $(NF-1) }' \
+		| sort -u \
+		| xargs -r dpkg-query --search \
+		| cut -d: -f1 \
+		| sort -u \
+		| xargs -r apt-mark manual \
+	&& apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
+	\
 	&& cd / \
 	&& rm -r /usr/src/ruby \
 # make sure bundled "rubygems" is older than RUBYGEMS_VERSION (https://github.com/docker-library/ruby/issues/246)
diff --git a/2.3/stretch/slim/Dockerfile b/2.3/stretch/slim/Dockerfile
index c72481c98..365f2faf7 100644
--- a/2.3/stretch/slim/Dockerfile
+++ b/2.3/stretch/slim/Dockerfile
@@ -28,7 +28,8 @@ ENV RUBYGEMS_VERSION 3.0.1
 #   we purge system ruby later to make sure our final image uses what we just built
 RUN set -ex \
 	\
-	&& buildDeps=' \
+	&& savedAptMark="$(apt-mark showmanual)" \
+	&& apt-get update && apt-get install -y --no-install-recommends \
 		autoconf \
 		bison \
 		dpkg-dev \
@@ -36,6 +37,7 @@ RUN set -ex \
 		libbz2-dev \
 		libgdbm-dev \
 		libglib2.0-dev \
+		libgmp-dev \
 		libncurses-dev \
 		libreadline-dev \
 		libxml2-dev \
@@ -44,9 +46,6 @@ RUN set -ex \
 		ruby \
 		wget \
 		xz-utils \
-	' \
-	&& apt-get update \
-	&& apt-get install -y --no-install-recommends $buildDeps \
 	&& rm -rf /var/lib/apt/lists/* \
 	\
 	&& wget -O ruby.tar.xz "https://cache.ruby-lang.org/pub/ruby/${RUBY_MAJOR%-rc}/ruby-$RUBY_VERSION.tar.xz" \
@@ -76,10 +75,17 @@ RUN set -ex \
 	&& make -j "$(nproc)" \
 	&& make install \
 	\
-	&& dpkg-query --show --showformat '${package}\n' \
-		| grep -P '^libreadline\d+$' \
-		| xargs apt-mark manual \
-	&& apt-get purge -y --auto-remove $buildDeps \
+	&& apt-mark auto '.*' > /dev/null \
+	&& apt-mark manual $savedAptMark \
+	&& find /usr/local -type f -executable -not \( -name '*tkinter*' \) -exec ldd '{}' ';' \
+		| awk '/=>/ { print $(NF-1) }' \
+		| sort -u \
+		| xargs -r dpkg-query --search \
+		| cut -d: -f1 \
+		| sort -u \
+		| xargs -r apt-mark manual \
+	&& apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
+	\
 	&& cd / \
 	&& rm -r /usr/src/ruby \
 # make sure bundled "rubygems" is older than RUBYGEMS_VERSION (https://github.com/docker-library/ruby/issues/246)
diff --git a/2.4/alpine3.8/Dockerfile b/2.4/alpine3.8/Dockerfile
index fdba4725d..92779e404 100644
--- a/2.4/alpine3.8/Dockerfile
+++ b/2.4/alpine3.8/Dockerfile
@@ -28,6 +28,7 @@ RUN set -ex \
 		gcc \
 		gdbm-dev \
 		glib-dev \
+		gmp-dev \
 		libc-dev \
 		libffi-dev \
 		libxml2-dev \
diff --git a/2.4/alpine3.9/Dockerfile b/2.4/alpine3.9/Dockerfile
index 92c39fc29..6ce8f4b06 100644
--- a/2.4/alpine3.9/Dockerfile
+++ b/2.4/alpine3.9/Dockerfile
@@ -28,6 +28,7 @@ RUN set -ex \
 		gcc \
 		gdbm-dev \
 		glib-dev \
+		gmp-dev \
 		libc-dev \
 		libffi-dev \
 		libxml2-dev \
diff --git a/2.4/jessie/slim/Dockerfile b/2.4/jessie/slim/Dockerfile
index 6feb049e2..49ee44bd2 100644
--- a/2.4/jessie/slim/Dockerfile
+++ b/2.4/jessie/slim/Dockerfile
@@ -28,7 +28,8 @@ ENV RUBYGEMS_VERSION 3.0.1
 #   we purge system ruby later to make sure our final image uses what we just built
 RUN set -ex \
 	\
-	&& buildDeps=' \
+	&& savedAptMark="$(apt-mark showmanual)" \
+	&& apt-get update && apt-get install -y --no-install-recommends \
 		autoconf \
 		bison \
 		dpkg-dev \
@@ -36,6 +37,7 @@ RUN set -ex \
 		libbz2-dev \
 		libgdbm-dev \
 		libglib2.0-dev \
+		libgmp-dev \
 		libncurses-dev \
 		libreadline-dev \
 		libxml2-dev \
@@ -44,9 +46,6 @@ RUN set -ex \
 		ruby \
 		wget \
 		xz-utils \
-	' \
-	&& apt-get update \
-	&& apt-get install -y --no-install-recommends $buildDeps \
 	&& rm -rf /var/lib/apt/lists/* \
 	\
 	&& wget -O ruby.tar.xz "https://cache.ruby-lang.org/pub/ruby/${RUBY_MAJOR%-rc}/ruby-$RUBY_VERSION.tar.xz" \
@@ -76,10 +75,17 @@ RUN set -ex \
 	&& make -j "$(nproc)" \
 	&& make install \
 	\
-	&& dpkg-query --show --showformat '${package}\n' \
-		| grep -P '^libreadline\d+$' \
-		| xargs apt-mark manual \
-	&& apt-get purge -y --auto-remove $buildDeps \
+	&& apt-mark auto '.*' > /dev/null \
+	&& apt-mark manual $savedAptMark \
+	&& find /usr/local -type f -executable -not \( -name '*tkinter*' \) -exec ldd '{}' ';' \
+		| awk '/=>/ { print $(NF-1) }' \
+		| sort -u \
+		| xargs -r dpkg-query --search \
+		| cut -d: -f1 \
+		| sort -u \
+		| xargs -r apt-mark manual \
+	&& apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
+	\
 	&& cd / \
 	&& rm -r /usr/src/ruby \
 # make sure bundled "rubygems" is older than RUBYGEMS_VERSION (https://github.com/docker-library/ruby/issues/246)
diff --git a/2.4/stretch/slim/Dockerfile b/2.4/stretch/slim/Dockerfile
index 0e8c1a2ee..34c9e302c 100644
--- a/2.4/stretch/slim/Dockerfile
+++ b/2.4/stretch/slim/Dockerfile
@@ -28,7 +28,8 @@ ENV RUBYGEMS_VERSION 3.0.1
 #   we purge system ruby later to make sure our final image uses what we just built
 RUN set -ex \
 	\
-	&& buildDeps=' \
+	&& savedAptMark="$(apt-mark showmanual)" \
+	&& apt-get update && apt-get install -y --no-install-recommends \
 		autoconf \
 		bison \
 		dpkg-dev \
@@ -36,6 +37,7 @@ RUN set -ex \
 		libbz2-dev \
 		libgdbm-dev \
 		libglib2.0-dev \
+		libgmp-dev \
 		libncurses-dev \
 		libreadline-dev \
 		libxml2-dev \
@@ -44,9 +46,6 @@ RUN set -ex \
 		ruby \
 		wget \
 		xz-utils \
-	' \
-	&& apt-get update \
-	&& apt-get install -y --no-install-recommends $buildDeps \
 	&& rm -rf /var/lib/apt/lists/* \
 	\
 	&& wget -O ruby.tar.xz "https://cache.ruby-lang.org/pub/ruby/${RUBY_MAJOR%-rc}/ruby-$RUBY_VERSION.tar.xz" \
@@ -76,10 +75,17 @@ RUN set -ex \
 	&& make -j "$(nproc)" \
 	&& make install \
 	\
-	&& dpkg-query --show --showformat '${package}\n' \
-		| grep -P '^libreadline\d+$' \
-		| xargs apt-mark manual \
-	&& apt-get purge -y --auto-remove $buildDeps \
+	&& apt-mark auto '.*' > /dev/null \
+	&& apt-mark manual $savedAptMark \
+	&& find /usr/local -type f -executable -not \( -name '*tkinter*' \) -exec ldd '{}' ';' \
+		| awk '/=>/ { print $(NF-1) }' \
+		| sort -u \
+		| xargs -r dpkg-query --search \
+		| cut -d: -f1 \
+		| sort -u \
+		| xargs -r apt-mark manual \
+	&& apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
+	\
 	&& cd / \
 	&& rm -r /usr/src/ruby \
 # make sure bundled "rubygems" is older than RUBYGEMS_VERSION (https://github.com/docker-library/ruby/issues/246)
diff --git a/2.5/alpine3.8/Dockerfile b/2.5/alpine3.8/Dockerfile
index 152c83197..50dce149d 100644
--- a/2.5/alpine3.8/Dockerfile
+++ b/2.5/alpine3.8/Dockerfile
@@ -28,6 +28,7 @@ RUN set -ex \
 		gcc \
 		gdbm-dev \
 		glib-dev \
+		gmp-dev \
 		libc-dev \
 		libffi-dev \
 		libxml2-dev \
diff --git a/2.5/alpine3.9/Dockerfile b/2.5/alpine3.9/Dockerfile
index 283f77b99..ccf57d9a9 100644
--- a/2.5/alpine3.9/Dockerfile
+++ b/2.5/alpine3.9/Dockerfile
@@ -28,6 +28,7 @@ RUN set -ex \
 		gcc \
 		gdbm-dev \
 		glib-dev \
+		gmp-dev \
 		libc-dev \
 		libffi-dev \
 		libxml2-dev \
diff --git a/2.5/stretch/slim/Dockerfile b/2.5/stretch/slim/Dockerfile
index ce8ec6316..255b02db5 100644
--- a/2.5/stretch/slim/Dockerfile
+++ b/2.5/stretch/slim/Dockerfile
@@ -28,7 +28,8 @@ ENV RUBYGEMS_VERSION 3.0.1
 #   we purge system ruby later to make sure our final image uses what we just built
 RUN set -ex \
 	\
-	&& buildDeps=' \
+	&& savedAptMark="$(apt-mark showmanual)" \
+	&& apt-get update && apt-get install -y --no-install-recommends \
 		autoconf \
 		bison \
 		dpkg-dev \
@@ -36,6 +37,7 @@ RUN set -ex \
 		libbz2-dev \
 		libgdbm-dev \
 		libglib2.0-dev \
+		libgmp-dev \
 		libncurses-dev \
 		libreadline-dev \
 		libxml2-dev \
@@ -44,9 +46,6 @@ RUN set -ex \
 		ruby \
 		wget \
 		xz-utils \
-	' \
-	&& apt-get update \
-	&& apt-get install -y --no-install-recommends $buildDeps \
 	&& rm -rf /var/lib/apt/lists/* \
 	\
 	&& wget -O ruby.tar.xz "https://cache.ruby-lang.org/pub/ruby/${RUBY_MAJOR%-rc}/ruby-$RUBY_VERSION.tar.xz" \
@@ -76,10 +75,17 @@ RUN set -ex \
 	&& make -j "$(nproc)" \
 	&& make install \
 	\
-	&& dpkg-query --show --showformat '${package}\n' \
-		| grep -P '^libreadline\d+$' \
-		| xargs apt-mark manual \
-	&& apt-get purge -y --auto-remove $buildDeps \
+	&& apt-mark auto '.*' > /dev/null \
+	&& apt-mark manual $savedAptMark \
+	&& find /usr/local -type f -executable -not \( -name '*tkinter*' \) -exec ldd '{}' ';' \
+		| awk '/=>/ { print $(NF-1) }' \
+		| sort -u \
+		| xargs -r dpkg-query --search \
+		| cut -d: -f1 \
+		| sort -u \
+		| xargs -r apt-mark manual \
+	&& apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
+	\
 	&& cd / \
 	&& rm -r /usr/src/ruby \
 # make sure bundled "rubygems" is older than RUBYGEMS_VERSION (https://github.com/docker-library/ruby/issues/246)
diff --git a/2.6/alpine3.8/Dockerfile b/2.6/alpine3.8/Dockerfile
index c81f291ff..4bb66c7ca 100644
--- a/2.6/alpine3.8/Dockerfile
+++ b/2.6/alpine3.8/Dockerfile
@@ -27,6 +27,7 @@ RUN set -ex \
 		gcc \
 		gdbm-dev \
 		glib-dev \
+		gmp-dev \
 		libc-dev \
 		libffi-dev \
 		libxml2-dev \
diff --git a/2.6/alpine3.9/Dockerfile b/2.6/alpine3.9/Dockerfile
index ab7dfbae8..72826da6b 100644
--- a/2.6/alpine3.9/Dockerfile
+++ b/2.6/alpine3.9/Dockerfile
@@ -27,6 +27,7 @@ RUN set -ex \
 		gcc \
 		gdbm-dev \
 		glib-dev \
+		gmp-dev \
 		libc-dev \
 		libffi-dev \
 		libxml2-dev \
diff --git a/2.6/stretch/slim/Dockerfile b/2.6/stretch/slim/Dockerfile
index 03d34b18a..438bc8f4d 100644
--- a/2.6/stretch/slim/Dockerfile
+++ b/2.6/stretch/slim/Dockerfile
@@ -27,7 +27,8 @@ ENV RUBY_DOWNLOAD_SHA256 47b629808e9fd44ce1f760cdf3ed14875fc9b19d4f334e82e2cf25c
 #   we purge system ruby later to make sure our final image uses what we just built
 RUN set -ex \
 	\
-	&& buildDeps=' \
+	&& savedAptMark="$(apt-mark showmanual)" \
+	&& apt-get update && apt-get install -y --no-install-recommends \
 		autoconf \
 		bison \
 		dpkg-dev \
@@ -35,6 +36,7 @@ RUN set -ex \
 		libbz2-dev \
 		libgdbm-dev \
 		libglib2.0-dev \
+		libgmp-dev \
 		libncurses-dev \
 		libreadline-dev \
 		libxml2-dev \
@@ -43,9 +45,6 @@ RUN set -ex \
 		ruby \
 		wget \
 		xz-utils \
-	' \
-	&& apt-get update \
-	&& apt-get install -y --no-install-recommends $buildDeps \
 	&& rm -rf /var/lib/apt/lists/* \
 	\
 	&& wget -O ruby.tar.xz "https://cache.ruby-lang.org/pub/ruby/${RUBY_MAJOR%-rc}/ruby-$RUBY_VERSION.tar.xz" \
@@ -75,10 +74,17 @@ RUN set -ex \
 	&& make -j "$(nproc)" \
 	&& make install \
 	\
-	&& dpkg-query --show --showformat '${package}\n' \
-		| grep -P '^libreadline\d+$' \
-		| xargs apt-mark manual \
-	&& apt-get purge -y --auto-remove $buildDeps \
+	&& apt-mark auto '.*' > /dev/null \
+	&& apt-mark manual $savedAptMark \
+	&& find /usr/local -type f -executable -not \( -name '*tkinter*' \) -exec ldd '{}' ';' \
+		| awk '/=>/ { print $(NF-1) }' \
+		| sort -u \
+		| xargs -r dpkg-query --search \
+		| cut -d: -f1 \
+		| sort -u \
+		| xargs -r apt-mark manual \
+	&& apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
+	\
 	&& cd / \
 	&& rm -r /usr/src/ruby \
 # rough smoke test
diff --git a/Dockerfile-alpine.template b/Dockerfile-alpine.template
index 5b28ebf81..7a07b247f 100644
--- a/Dockerfile-alpine.template
+++ b/Dockerfile-alpine.template
@@ -28,6 +28,7 @@ RUN set -ex \
 		gcc \
 		gdbm-dev \
 		glib-dev \
+		gmp-dev \
 		libc-dev \
 		libffi-dev \
 		libxml2-dev \
diff --git a/Dockerfile-slim.template b/Dockerfile-slim.template
index d0d5e6629..2fde2d1b3 100644
--- a/Dockerfile-slim.template
+++ b/Dockerfile-slim.template
@@ -28,7 +28,8 @@ ENV RUBYGEMS_VERSION %%RUBYGEMS%%
 #   we purge system ruby later to make sure our final image uses what we just built
 RUN set -ex \
 	\
-	&& buildDeps=' \
+	&& savedAptMark="$(apt-mark showmanual)" \
+	&& apt-get update && apt-get install -y --no-install-recommends \
 		autoconf \
 		bison \
 		dpkg-dev \
@@ -36,6 +37,7 @@ RUN set -ex \
 		libbz2-dev \
 		libgdbm-dev \
 		libglib2.0-dev \
+		libgmp-dev \
 		libncurses-dev \
 		libreadline-dev \
 		libxml2-dev \
@@ -44,9 +46,6 @@ RUN set -ex \
 		ruby \
 		wget \
 		xz-utils \
-	' \
-	&& apt-get update \
-	&& apt-get install -y --no-install-recommends $buildDeps \
 	&& rm -rf /var/lib/apt/lists/* \
 	\
 	&& wget -O ruby.tar.xz "https://cache.ruby-lang.org/pub/ruby/${RUBY_MAJOR%-rc}/ruby-$RUBY_VERSION.tar.xz" \
@@ -76,10 +75,17 @@ RUN set -ex \
 	&& make -j "$(nproc)" \
 	&& make install \
 	\
-	&& dpkg-query --show --showformat '${package}\n' \
-		| grep -P '^libreadline\d+$' \
-		| xargs apt-mark manual \
-	&& apt-get purge -y --auto-remove $buildDeps \
+	&& apt-mark auto '.*' > /dev/null \
+	&& apt-mark manual $savedAptMark \
+	&& find /usr/local -type f -executable -not \( -name '*tkinter*' \) -exec ldd '{}' ';' \
+		| awk '/=>/ { print $(NF-1) }' \
+		| sort -u \
+		| xargs -r dpkg-query --search \
+		| cut -d: -f1 \
+		| sort -u \
+		| xargs -r apt-mark manual \
+	&& apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
+	\
 	&& cd / \
 	&& rm -r /usr/src/ruby \
 # make sure bundled "rubygems" is older than RUBYGEMS_VERSION (https://github.com/docker-library/ruby/issues/246)