diff --git a/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.mask b/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.mask
index d09537a81b..27dd2945be 100644
--- a/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.mask
+++ b/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.mask
@@ -20,3 +20,8 @@
 
 # Pulls in LLVM and clang.
 >=sys-block/thin-provisioning-tools-1.0.14
+
+# Too large to fit into our /boot partition - the size grew by 3MB. We
+mask a specific version in hope that the future update may be smaller,
+who knows.
+=sys-firmware/intel-microcode-20250512_p20250513