diff --git a/ci-operator/config/openshift/os/openshift-os-release-4.14.yaml b/ci-operator/config/openshift/os/openshift-os-release-4.14.yaml
index bceb2048c4a20..d3182b9831012 100644
--- a/ci-operator/config/openshift/os/openshift-os-release-4.14.yaml
+++ b/ci-operator/config/openshift/os/openshift-os-release-4.14.yaml
@@ -1,8 +1,8 @@
 base_images:
-  coreos_coreos-assembler_latest:
+  coreos_coreos-assembler_4.14:
     name: coreos-assembler
     namespace: coreos
-    tag: latest
+    tag: "4.14"
 build_root:
   image_stream_tag:
     name: fcos-buildroot
@@ -11,7 +11,7 @@ build_root:
 images:
 - dockerfile_literal: |
     # COSA + source code
-    FROM registry.ci.openshift.org/coreos/coreos-assembler:latest
+    FROM registry.ci.openshift.org/coreos/coreos-assembler:4.14
     WORKDIR /src
     # Tell the build scripts that we have setup a directory for unprivileged build
     ENV COSA_DIR=/tmp/cosa
@@ -30,9 +30,9 @@ images:
     USER builder
     WORKDIR /tmp/cosa
   inputs:
-    coreos_coreos-assembler_latest:
+    coreos_coreos-assembler_4.14:
       as:
-      - registry.ci.openshift.org/coreos/coreos-assembler:latest
+      - registry.ci.openshift.org/coreos/coreos-assembler:4.14
   to: build-image
 promotion:
   to:
diff --git a/ci-operator/config/openshift/os/openshift-os-release-4.15.yaml b/ci-operator/config/openshift/os/openshift-os-release-4.15.yaml
index cab0df7195cc2..8cb027ad3b55a 100644
--- a/ci-operator/config/openshift/os/openshift-os-release-4.15.yaml
+++ b/ci-operator/config/openshift/os/openshift-os-release-4.15.yaml
@@ -1,8 +1,8 @@
 base_images:
-  coreos_coreos-assembler_latest:
+  coreos_coreos-assembler_4.15:
     name: coreos-assembler
     namespace: coreos
-    tag: latest
+    tag: "4.15"
 build_root:
   image_stream_tag:
     name: fcos-buildroot
@@ -11,7 +11,7 @@ build_root:
 images:
 - dockerfile_literal: |
     # COSA + source code
-    FROM registry.ci.openshift.org/coreos/coreos-assembler:latest
+    FROM registry.ci.openshift.org/coreos/coreos-assembler:4.15
     WORKDIR /src
     # Tell the build scripts that we have setup a directory for unprivileged build
     ENV COSA_DIR=/tmp/cosa
@@ -30,9 +30,9 @@ images:
     USER builder
     WORKDIR /tmp/cosa
   inputs:
-    coreos_coreos-assembler_latest:
+    coreos_coreos-assembler_4.15:
       as:
-      - registry.ci.openshift.org/coreos/coreos-assembler:latest
+      - registry.ci.openshift.org/coreos/coreos-assembler:4.15
   to: build-image
 promotion:
   to: