diff --git a/.github/workflows/push_to_docker_hub.yml b/.github/workflows/push_to_docker_hub.yml
index cd289f6a88b..aeb23cf4de0 100644
--- a/.github/workflows/push_to_docker_hub.yml
+++ b/.github/workflows/push_to_docker_hub.yml
@@ -1,10 +1,12 @@
 name: Build Docker images and push to DockerHub
 
 on:
+  pull_request:
+    paths:
+      - '.github/workflows/push_to_docker_hub.yml'
+      - 'docker/Dockerfile'
   workflow_dispatch:
     # Allow to run manually
-    branches:
-      - 'develop'
   push:
     tags:
       # Match all release tags including beta, rc
diff --git a/docker/Dockerfile b/docker/Dockerfile
index 101f50b5860..3bbce529dbd 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -78,9 +78,9 @@ ARG MAKE_BUILD=make-build
 FROM ubuntu:jammy AS run-time-dependencies
 LABEL maintainer="Erik M. Bray <erik.bray@lri.fr>, Julian Rüth <julian.rueth@fsfe.org>, Sebastian Oehms <seb.oehms@gmail.com>"
 # Set sane defaults for common environment variables.
-ENV LC_ALL C.UTF-8
-ENV LANG C.UTF-8
-ENV SHELL /bin/bash
+ENV LC_ALL=C.UTF-8
+ENV LANG=C.UTF-8
+ENV SHELL=/bin/bash
 # Create symlinks for sage and sagemath - we copy a built sage to the target of these symlinks later.
 ARG SAGE_ROOT=/home/sage/sage
 RUN ln -s "$SAGE_ROOT/sage" /usr/bin/sage
@@ -90,7 +90,7 @@ RUN ln -s /usr/bin/sage /usr/bin/sagemath
 # We need gcc/g++ and libstdc++-10-dev to allow compilation of cython at run-time from the notebook.
 # We also install sudo for the sage user, see below.
 RUN apt-get -qq update \
-    && apt-get -qq install -y --no-install-recommends gfortran gcc g++ libstdc++-10-dev sudo openssl bzip2 libbz2-dev pkg-config\
+    && apt-get -qq install -y --no-install-recommends gfortran gcc g++ libstdc++-10-dev sudo openssl pkg-config patch libz-dev libbz2-dev bzip2 ca-certificates perl \
     && apt-get -qq clean \
     && rm -r /var/lib/apt/lists/*
 # Sage refuses to build as root, so we add a "sage" user that can sudo without a password.
@@ -101,7 +101,7 @@ RUN adduser --quiet --shell /bin/bash --gecos "Sage user,101,," --disabled-passw
     && chmod 0440 /etc/sudoers.d/01-sage
 # Run everything from now on as the sage user in sage's home
 USER sage
-ENV HOME $HOME
+ENV HOME=$HOME
 WORKDIR $HOME
 
 ################################################################################
@@ -111,7 +111,7 @@ WORKDIR $HOME
 FROM run-time-dependencies AS build-time-dependencies
 # Install the build time dependencies & git & rdfind
 RUN sudo apt-get -qq update \
-    && sudo apt-get -qq install -y wget build-essential automake m4 dpkg-dev python3 libssl-dev git rdfind \
+    && sudo apt-get -qq install -y wget build-essential automake m4 dpkg-dev python3 libssl-dev git rdfind autoconf automake libtool bc binutils \
     && sudo apt-get -qq clean \
     && sudo rm -r /var/lib/apt/lists/*
 
@@ -185,17 +185,17 @@ RUN patch -p1 < "$HOME"/sage-context.patch
 ################################################################################
 FROM source-from-context AS make-build
 # Make sure that the result runs on most CPUs.
-ENV SAGE_FAT_BINARY yes
+ENV SAGE_FAT_BINARY=yes
 # Just to be sure Sage doesn't try to build its own GCC (even though
 # it shouldn't with a recent GCC package from the system and with gfortran)
-ENV SAGE_INSTALL_GCC no
+ENV SAGE_INSTALL_GCC=no
 # Set MAKEFLAGS and SAGE_NUM_THREADS to build things in parallel during the
 # docker build. Note that these do not leak into the sagemath and sagemath-dev
 # images.
 ARG MAKEFLAGS="-j2"
-ENV MAKEFLAGS $MAKEFLAGS
+ENV MAKEFLAGS=$MAKEFLAGS
 ARG SAGE_NUM_THREADS="2"
-ENV SAGE_NUM_THREADS $SAGE_NUM_THREADS
+ENV SAGE_NUM_THREADS=$SAGE_NUM_THREADS
 RUN make configure
 # Old default before https://github.com/sagemath/sage/issues/32406
 RUN ./configure --disable-editable
@@ -210,9 +210,9 @@ FROM $MAKE_BUILD AS make-all
 # overcommit limit of the system (no RAM is actually used, but this limit is
 # very low because there is not even swap on most CI systems.)
 ARG MAKEFLAGS_DOCBUILD=$MAKEFLAGS
-ENV MAKEFLAGS_DOCBUILD $MAKEFLAGS_DOCBUILD
+ENV MAKEFLAGS_DOCBUILD=$MAKEFLAGS_DOCBUILD
 ARG SAGE_NUM_THREADS_DOCBUILD=$SAGE_NUM_THREADS
-ENV SAGE_NUM_THREADS $SAGE_NUM_THREADS_DOCBUILD
+ENV SAGE_NUM_THREADS=$SAGE_NUM_THREADS_DOCBUILD
 RUN make
 
 ################################################################################