diff --git a/github/repos_rules.go b/github/repos_rules.go
index 4e6f5f13474..38d4255a9aa 100644
--- a/github/repos_rules.go
+++ b/github/repos_rules.go
@@ -118,6 +118,10 @@ func (r *RepositoryRule) UnmarshalJSON(data []byte) error {
 	case "creation", "deletion", "required_linear_history", "required_signatures", "non_fast_forward":
 		r.Parameters = nil
 	case "update":
+		if RepositoryRule.Parameters == nil {
+			r.Parameters = nil
+			return nil
+		}
 		params := UpdateAllowsFetchAndMergeRuleParameters{}
 		if err := json.Unmarshal(*RepositoryRule.Parameters, &params); err != nil {
 			return err
@@ -127,6 +131,7 @@ func (r *RepositoryRule) UnmarshalJSON(data []byte) error {
 		rawParams := json.RawMessage(bytes)
 
 		r.Parameters = &rawParams
+
 	case "required_deployments":
 		params := RequiredDeploymentEnvironmentsRuleParameters{}
 		if err := json.Unmarshal(*RepositoryRule.Parameters, &params); err != nil {
@@ -185,13 +190,18 @@ func NewCreationRule() (rule *RepositoryRule) {
 
 // NewUpdateRule creates a rule to only allow users with bypass permission to update matching refs.
 func NewUpdateRule(params *UpdateAllowsFetchAndMergeRuleParameters) (rule *RepositoryRule) {
-	bytes, _ := json.Marshal(params)
+	if params != nil {
+		bytes, _ := json.Marshal(params)
 
-	rawParams := json.RawMessage(bytes)
+		rawParams := json.RawMessage(bytes)
 
+		return &RepositoryRule{
+			Type:       "update",
+			Parameters: &rawParams,
+		}
+	}
 	return &RepositoryRule{
-		Type:       "update",
-		Parameters: &rawParams,
+		Type: "update",
 	}
 }
 
diff --git a/github/repos_rules_test.go b/github/repos_rules_test.go
index 582ec89245b..a57137c688d 100644
--- a/github/repos_rules_test.go
+++ b/github/repos_rules_test.go
@@ -292,6 +292,45 @@ func TestRepositoriesService_GetRulesForBranch(t *testing.T) {
 	})
 }
 
+func TestRepositoriesService_GetRulesForBranchEmptyUpdateRule(t *testing.T) {
+	client, mux, _, teardown := setup()
+	defer teardown()
+
+	mux.HandleFunc("/repos/o/repo/rules/branches/branch", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "GET")
+		fmt.Fprint(w, `[
+			{
+			  "type": "update"
+			}
+		]`)
+	})
+
+	ctx := context.Background()
+	rules, _, err := client.Repositories.GetRulesForBranch(ctx, "o", "repo", "branch")
+	if err != nil {
+		t.Errorf("Repositories.GetRulesForBranch returned error: %v", err)
+	}
+
+	updateRule := NewUpdateRule(nil)
+
+	want := []*RepositoryRule{
+		updateRule,
+	}
+	if !cmp.Equal(rules, want) {
+		t.Errorf("Repositories.GetRulesForBranch returned %+v, want %+v", Stringify(rules), Stringify(want))
+	}
+
+	const methodName = "GetRulesForBranch"
+
+	testNewRequestAndDoFailure(t, methodName, client, func() (*Response, error) {
+		got, resp, err := client.Repositories.GetRulesForBranch(ctx, "o", "repo", "branch")
+		if got != nil {
+			t.Errorf("testNewRequestAndDoFailure %v = %#v, want nil", methodName, got)
+		}
+		return resp, err
+	})
+}
+
 func TestRepositoriesService_GetAllRulesets(t *testing.T) {
 	client, mux, _, teardown := setup()
 	defer teardown()