diff --git a/changelog/changes/2025-04-17-vmlinuz-compression.md b/changelog/changes/2025-04-17-vmlinuz-compression.md
new file mode 100644
index 0000000000..707df0739e
--- /dev/null
+++ b/changelog/changes/2025-04-17-vmlinuz-compression.md
@@ -0,0 +1 @@
+- The kernel image and its embedded initrd are now compressed with xz rather than zstd. This gives greater compression at the cost of decompression performance. Systems may therefore now be ever so slightly slower to boot, but this was necessary to avoid running out of space in the /boot partition. Further measures to address the space issue are planned, and perhaps we can switch back to zstd in a later release.
diff --git a/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/commonconfig-6.6 b/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/commonconfig-6.6
index d5274957c3..841c800754 100644
--- a/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/commonconfig-6.6
+++ b/sdk_container/src/third_party/coreos-overlay/sys-kernel/coreos-modules/files/commonconfig-6.6
@@ -292,7 +292,7 @@ CONFIG_INFINIBAND_MTHCA=m
 CONFIG_INFINIBAND_OCRDMA=m
 CONFIG_INFINIBAND_SRP=m
 CONFIG_INFINIBAND_USER_MAD=m
-CONFIG_INITRAMFS_COMPRESSION_ZSTD=y
+CONFIG_INITRAMFS_COMPRESSION_XZ=y
 CONFIG_INIT_STACK_NONE=y
 CONFIG_INPUT_EVDEV=m
 CONFIG_INPUT_MISC=y