diff --git a/sdk_container/src/third_party/coreos-overlay/coreos/config/env/sys-devel/flex b/sdk_container/src/third_party/coreos-overlay/coreos/config/env/sys-devel/flex
new file mode 100644
index 0000000000..bfea8f4030
--- /dev/null
+++ b/sdk_container/src/third_party/coreos-overlay/coreos/config/env/sys-devel/flex
@@ -0,0 +1 @@
+export EXTRA_ECONF="--disable-bootstrap"
diff --git a/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.accept_keywords b/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.accept_keywords
index a0d0a10fb0..6440e68114 100644
--- a/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.accept_keywords
+++ b/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/package.accept_keywords
@@ -108,3 +108,6 @@ dev-util/checkbashisms
 
 # multipath-tools 0.6.2 fixes systemd dependencies
 =sys-fs/multipath-tools-0.6.2-r2
+
+# flex 2.6.1 breaks cross-compiling, but 2.6.3 adds a configure workaround
+=sys-devel/flex-2.6.3 **