diff --git a/ci/ciimage/opensuse/install.sh b/ci/ciimage/opensuse/install.sh
index 7de18ecb6..fdfedcb1b 100755
--- a/ci/ciimage/opensuse/install.sh
+++ b/ci/ciimage/opensuse/install.sh
@@ -35,6 +35,9 @@ echo 'export PKG_CONFIG_PATH="/usr/lib64/mpi/gcc/openmpi3/lib64/pkgconfig:$PKG_C
 curl -fsS https://dlang.org/install.sh | bash -s dmd | tee dmd_out.txt
 cat dmd_out.txt | grep source | sed 's/^[^`]*`//g' | sed 's/`.*//g' >> /ci/env_vars.sh
 chmod +x /ci/env_vars.sh
+# Lower ulimit before running dub, otherwise there's a very high chance it will OOM.
+# See: https://github.com/dlang/phobos/pull/9048 and https://github.com/dlang/phobos/pull/8990
+echo 'ulimit -n -S 10000' >> /ci/env_vars.sh
 
 source /ci/env_vars.sh
 
diff --git a/ci/ciimage/ubuntu-rolling/install.sh b/ci/ciimage/ubuntu-rolling/install.sh
index 1706d837d..2066944e4 100755
--- a/ci/ciimage/ubuntu-rolling/install.sh
+++ b/ci/ciimage/ubuntu-rolling/install.sh
@@ -44,6 +44,10 @@ eatmydata apt-get -y install --no-install-recommends wine-stable  # Wine is spec
 
 install_python_packages hotdoc
 
+# Lower ulimit before running dub, otherwise there's a very high chance it will OOM.
+# See: https://github.com/dlang/phobos/pull/9048 and https://github.com/dlang/phobos/pull/8990
+echo 'ulimit -n -S 10000' >> /ci/env_vars.sh
+ulimit -n -S 10000
 # dub stuff
 dub_fetch urld
 dub build --deep urld --arch=x86_64 --compiler=gdc --build=debug