diff --git a/hack/lib/init.sh b/hack/lib/init.sh
index 17f69c91c53..90086ad830a 100755
--- a/hack/lib/init.sh
+++ b/hack/lib/init.sh
@@ -18,6 +18,9 @@ set -o errexit
 set -o nounset
 set -o pipefail
 
+# Short-circuit if init.sh has already been sourced
+[[ $(type -t kube::init::loaded) == function ]] && return 0
+
 # Unset CDPATH so that path interpolation can work correctly
 # https://github.com/kubernetes/kubernetes/issues/52255
 unset CDPATH
@@ -211,3 +214,8 @@ kube::realpath() {
   fi
   kube::readlinkdashf "${1}"
 }
+
+# Marker function to indicate init.sh has been fully sourced
+kube::init::loaded() {
+  return 0
+}
diff --git a/hack/lib/protoc.sh b/hack/lib/protoc.sh
index 4c8a3920146..6b080084a92 100644
--- a/hack/lib/protoc.sh
+++ b/hack/lib/protoc.sh
@@ -18,6 +18,9 @@ set -o errexit
 set -o nounset
 set -o pipefail
 
+# Short-circuit if protoc.sh has already been sourced
+[[ $(type -t kube::protoc::loaded) == function ]] && return 0
+
 # The root of the build/dist directory
 KUBE_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd -P)"
 source "${KUBE_ROOT}/hack/lib/init.sh"
@@ -134,3 +137,8 @@ function kube::protoc::install() {
     kube::log::info "export PATH=\"$(pwd)/protoc:\${PATH}\""
   )
 }
+
+# Marker function to indicate protoc.sh has been fully sourced
+kube::protoc::loaded() {
+  return 0
+}