diff --git a/main.go b/main.go
index 132be61..91661f0 100644
--- a/main.go
+++ b/main.go
@@ -38,8 +38,11 @@ func main() {
 	}
 
 	// Limit number of iterations.
+	from := gha.GetInput("from")
+	log.Printf("Resolving revision '%s'", from)
+
 	var lca *object.Commit
-	if from := gha.GetInput("from"); from != "" {
+	if from != "" {
 		lca = getMergeBase(r, head, from)
 	}
 
@@ -75,6 +78,7 @@ func main() {
 		if !rxSignOff.MatchString(lines[len(lines)-1]) {
 			fail = true
 			fmt.Printf("Error: missing sign-off %s [%s]\n", header, id)
+			return nil
 		}
 
 		return nil
@@ -89,7 +93,10 @@ func main() {
 func getMergeBase(r *git.Repository, head *plumbing.Reference, from string) *object.Commit {
 	h, err := r.ResolveRevision(plumbing.Revision(from))
 	if err != nil {
-		log.Fatalf("Failed to resolve a reference: %v", err)
+		h, err = r.ResolveRevision(plumbing.Revision(plumbing.NewBranchReferenceName(from)))
+		if err != nil {
+			log.Fatalf("Failed to resolve a reference '%s': %v", from, err)
+		}
 	}
 
 	to, err := r.CommitObject(*h)