diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 00000000..1079f741
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,8 @@
+# The build image only needs a couple of scripts out of the tree, so keep the
+# build context from dragging in a full local build.
+.git
+objs/
+bins/
+/pcsx-redux
+/pcsx-redux-tests
+*.AppImage
diff --git a/tools/build/Dockerfile b/tools/build/Dockerfile
index 4ac6eb1d..ae7b94ab 100644
--- a/tools/build/Dockerfile
+++ b/tools/build/Dockerfile
@@ -1,4 +1,25 @@
 # Dockerfile for ghcr.io/grumpycoders/pcsx-redux-build
+#
+# This one needs the repository root as its build context, as the first stage
+# builds the mips toolchain using tools/linux-mips/spawn-compiler.sh:
+#
+#   docker build -f tools/build/Dockerfile -t ghcr.io/grumpycoders/pcsx-redux-build .
+
+FROM ubuntu:26.04 AS toolchain
+
+ENV DEBIAN_FRONTEND noninteractive
+ENV TZ Etc/GMT
+
+RUN apt update
+RUN apt dist-upgrade -y
+RUN apt install -y make g++ wget bzip2 xz-utils bison flex texinfo
+RUN apt install -y libgmp-dev libmpfr-dev libmpc-dev
+
+ARG JOBS=
+
+WORKDIR /tmp/toolchain
+COPY tools/linux-mips/spawn-compiler.sh .
+RUN JOBS=$JOBS sh spawn-compiler.sh
 
 FROM ubuntu:26.04
 
@@ -16,7 +37,6 @@ RUN apt install -y pkg-config
 
 # Compilers & base libraries
 RUN apt install -y g++
-RUN apt install -y g++-mipsel-linux-gnu
 
 # Development packages
 RUN apt install -y libavcodec-dev
@@ -33,7 +53,7 @@ RUN apt install -y zlib1g-dev
 # CI utilities
 RUN apt install -y curl wget
 RUN apt install -y xvfb
-RUN apt install -y python3-pip python3-setuptools patchelf desktop-file-utils libgdk-pixbuf2.0-dev fakeroot strace
+RUN apt install -y python3-pip python3-setuptools patchelf desktop-file-utils libgdk-pixbuf-2.0-dev fakeroot strace
 RUN apt install -y glibc-tools lcov
 RUN apt install -y file
 
@@ -42,9 +62,13 @@ RUN apt install -y libfuse2t64
 RUN apt install -y fuse
 
 # AppImage tools
-RUN apt install -y imagemagick-6.q16 gtk-update-icon-cache appstream
+RUN apt install -y imagemagick-7.q16 gtk-update-icon-cache appstream
 RUN apt install -y squashfs-tools zip zsync
 
+# The mips toolchain, built from source in the first stage. Ubuntu dropped the
+# mipsel cross compilers, so there's no distribution package to install here.
+COPY --from=toolchain /usr/local /usr/local
+
 WORKDIR /tmp
 RUN wget https://github.com/AppImage/appimagetool/releases/download/continuous/appimagetool-x86_64.AppImage && \
     chmod +x appimagetool-x86_64.AppImage && \
diff --git a/tools/linux-mips/spawn-compiler.sh b/tools/linux-mips/spawn-compiler.sh
index d0d9eeda..9e20479d 100755
--- a/tools/linux-mips/spawn-compiler.sh
+++ b/tools/linux-mips/spawn-compiler.sh
@@ -1,17 +1,18 @@
 #!/bin/sh
 #
 # Building gcc from source isn't necessarily an easy task, and it requires
-# a lot of various dependency packages to work properly. The easiest way
-# to use a mips compiler for Linux is still to use a package from your
-# distribution. Nevertheless, here's how to build a working mips compiler
-# that can produce code for the R3000A CPU, granted you have the necessary
-# dependencies to do so. The script can be run as root, or as a regular user
-# when the PREFIX environment variable is provided.
+# a lot of various dependency packages to work properly. Here's how to build
+# a working mips compiler that can produce code for the R3000A CPU, granted
+# you have the necessary dependencies to do so. The script can be run as
+# root, or as a regular user when the PREFIX environment variable is
+# provided. Set JOBS to override the parallelism, which defaults to the
+# number of available cores.
 #
 
 set -ex
 
 PREFIX=${PREFIX:-"/usr/local"}
+JOBS=${JOBS:-$(nproc 2> /dev/null || echo 1)}
 
 for url in https://ftpmirror.gnu.org/gnu/binutils/binutils-2.47.tar.gz https://mirrors.kernel.org/gnu/binutils/binutils-2.47.tar.gz ; do
     wget --max-redirect=2 --timeout=60 --continue --trust-server-names $url && break
@@ -19,7 +20,7 @@ done
 tar xvfz binutils-2.47.tar.gz
 cd binutils-2.47
 ./configure --target=mipsel-none-elf --disable-multilib --disable-nls --disable-werror --prefix=$PREFIX
-make
+make -j$JOBS
 make install-strip
 cd ..
 
@@ -32,9 +33,9 @@ cd gcc-16.2.0
 mkdir build
 cd build
 ../configure --target=mipsel-none-elf --without-isl --disable-nls --disable-threads --disable-shared --disable-libssp --disable-libstdcxx-pch --disable-libgomp --disable-werror --without-headers --disable-hosted-libstdcxx --with-as=$PREFIX/bin/mipsel-none-elf-as --with-ld=$PREFIX/bin/mipsel-none-elf-ld --enable-languages=c,c++ --prefix=$PREFIX
-make all-gcc
+make -j$JOBS all-gcc
 make install-strip-gcc
-make all-target-libgcc
+make -j$JOBS all-target-libgcc
 make install-strip-target-libgcc
-make all-target-libstdc++-v3
+make -j$JOBS all-target-libstdc++-v3
 make install-strip-target-libstdc++-v3