diff --git a/functions-common b/functions-common
index 061a935..5f22bf0 100644
--- a/functions-common
+++ b/functions-common
@@ -36,6 +36,10 @@
 XTRACE=$(set +o | grep xtrace)
 set +o xtrace
 
+# ensure we don't re-source this in the same environment
+[[ -z "$_DEVSTACK_FUNCTIONS_COMMON" ]] || return 0
+declare -r _DEVSTACK_FUNCTIONS_COMMON=1
+
 # Global Config Variables
 declare -A GITREPO
 declare -A GITBRANCH