diff --git a/merge/entrypoint.sh b/merge/entrypoint.sh
index 08e0dcd..f884070 100755
--- a/merge/entrypoint.sh
+++ b/merge/entrypoint.sh
@@ -60,11 +60,24 @@ git remote prune origin
 failures=()
 
 function open_and_merge_pull_request() {
+    local source_branch="${GITHUB_REF#refs/heads/}"
+
     echo "DEBUG: making pull request from ${GITHUB_REF} to $1"
 
-    # if $1 branch does not exist origin
+    # if destination branch does not exist on origin
     if [[ -z "$(git ls-remote origin "$1")" ]]; then
         echo "Could not find expected branch '$1' on remote 'origin'"
+        return 1
+    fi
+
+    # Skip no-op merges so identical branches do not fail PR creation with
+    # "No commits between ..." validation errors.
+    local ahead_commit
+    ahead_commit="$(git rev-list --max-count=1 "origin/$1..origin/${source_branch}")"
+
+    if [[ -z "${ahead_commit}" ]]; then
+        echo "DEBUG: skipping merge of ${GITHUB_REF} into $1; ${source_branch} has no commits ahead of $1"
+        return 0
     fi
 
     # subshell with +e so we continue on errors