diff --git a/dockerfiles/manylinux_ghr_x86_64.Dockerfile b/dockerfiles/manylinux_ghr_x86_64.Dockerfile
index 5f50894..2bba379 100644
--- a/dockerfiles/manylinux_ghr_x86_64.Dockerfile
+++ b/dockerfiles/manylinux_ghr_x86_64.Dockerfile
@@ -1,7 +1,7 @@
 # We build our portable linux releases on the manylinux (RHEL-based)
 # images, with custom additional packages installed. We switch to
 # new upstream versions as needed.
-FROM quay.io/pypa/manylinux_2_28_x86_64
+FROM quay.io/pypa/manylinux_2_28_x86_64@sha256:9042a22d33af2223ff7a3599f236aff1e4ffd07e1ed1ac93a58877638317515f
 
 ARG GH_RUNNER_VERSION="2.314.1"
 ARG TARGETPLATFORM
diff --git a/dockerfiles/manylinux_x86_64.Dockerfile b/dockerfiles/manylinux_x86_64.Dockerfile
index c40f80b..105e71d 100644
--- a/dockerfiles/manylinux_x86_64.Dockerfile
+++ b/dockerfiles/manylinux_x86_64.Dockerfile
@@ -1,7 +1,7 @@
 # We build our portable linux releases on the manylinux (RHEL-based)
 # images, with custom additional packages installed. We switch to
 # new upstream versions as needed.
-FROM quay.io/pypa/manylinux_2_28_x86_64
+FROM quay.io/pypa/manylinux_2_28_x86_64@sha256:9042a22d33af2223ff7a3599f236aff1e4ffd07e1ed1ac93a58877638317515f
 
 RUN yum install -y epel-release && \
     yum install -y ccache clang lld && \