diff --git a/util/argo/argo.go b/util/argo/argo.go
index b8535e20ec6c0..1dda11f167019 100644
--- a/util/argo/argo.go
+++ b/util/argo/argo.go
@@ -348,9 +348,9 @@ func GetRefSources(ctx context.Context, spec argoappv1.ApplicationSpec, db db.Ar
 		refKeys := make(map[string]bool)
 		for _, source := range spec.Sources {
 			if source.Ref != "" {
-				isValidRefKey := regexp.MustCompile(`^[a-zA-Z0-9]+$`).MatchString
+				isValidRefKey := regexp.MustCompile(`^[a-zA-Z0-9_-]+$`).MatchString
 				if !isValidRefKey(source.Ref) {
-					return nil, fmt.Errorf("source.ref %s cannot contain any special characters except '_' and '-'", source.Ref)
+					return nil, fmt.Errorf("sources.ref %s cannot contain any special characters except '_' and '-'", source.Ref)
 				}
 				refKey := "$" + source.Ref
 				if _, ok := refKeys[refKey]; ok {
diff --git a/util/argo/argo_test.go b/util/argo/argo_test.go
index d44aa7f6134b7..1e883f5e0b8c4 100644
--- a/util/argo/argo_test.go
+++ b/util/argo/argo_test.go
@@ -1043,14 +1043,14 @@ func Test_GetRefSources(t *testing.T) {
 		repoDB.On("GetRepository", context.Background(), repo.Repo).Return(repo, nil)
 
 		argoSpec := getMultiSourceAppSpec(argoappv1.ApplicationSources{
-			{RepoURL: fmt.Sprintf("file://%s", repoPath), Ref: "source1"},
+			{RepoURL: fmt.Sprintf("file://%s", repoPath), Ref: "source-1_2"},
 			{RepoURL: fmt.Sprintf("file://%s", repoPath)},
 		})
 
 		refSources, err := GetRefSources(context.TODO(), *argoSpec, repoDB)
 
 		expectedRefSource := argoappv1.RefTargetRevisionMapping{
-			"$source1": &argoappv1.RefTarget{
+			"$source-1_2": &argoappv1.RefTarget{
 				Repo: *repo,
 			},
 		}