diff --git a/src/main/java/org/springframework/data/release/issues/github/GitHubIssue.java b/src/main/java/org/springframework/data/release/issues/github/GitHubIssue.java
index e8780f7..0277822 100644
--- a/src/main/java/org/springframework/data/release/issues/github/GitHubIssue.java
+++ b/src/main/java/org/springframework/data/release/issues/github/GitHubIssue.java
@@ -24,6 +24,8 @@ import java.util.List;
 import org.springframework.data.release.model.ModuleIteration;
 import org.springframework.util.Assert;
 
+import com.fasterxml.jackson.annotation.JsonIgnore;
+
 /**
  * @author Oliver Gierke
  * @author Mark Paluch
@@ -72,6 +74,7 @@ class GitHubIssue {
 			return title.contains(moduleIteration.getShortVersionString());
 		}
 
+		@JsonIgnore
 		public boolean isOpen() {
 			return "open".equals(state);
 		}
diff --git a/src/test/java/org/springframework/data/release/issues/github/GitHubIssueUnitTests.java b/src/test/java/org/springframework/data/release/issues/github/GitHubIssueUnitTests.java
new file mode 100644
index 0000000..995ece9
--- /dev/null
+++ b/src/test/java/org/springframework/data/release/issues/github/GitHubIssueUnitTests.java
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.release.issues.github;
+
+import static org.assertj.core.api.Assertions.*;
+
+import java.io.IOException;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.json.JsonTest;
+import org.springframework.boot.test.json.JacksonTester;
+import org.springframework.data.release.issues.github.GitHubIssue.Milestone;
+import org.springframework.test.context.junit4.SpringRunner;
+
+/**
+ * Unit tests for {@link GitHubIssue}.
+ *
+ * @author Mark Paluch
+ */
+@RunWith(SpringRunner.class)
+@JsonTest
+public class GitHubIssueUnitTests {
+
+	@Autowired private JacksonTester<Milestone> json;
+
+	@Test
+	public void shouldNotRenderOpenProperty() throws IOException {
+
+		Milestone milestone = Milestone.of("my-title", "my-description");
+
+		assertThat(this.json.write(milestone)) //
+				.hasJsonPathStringValue("@.title", "my-title") //
+				.hasJsonPathStringValue("@.description", "my-description") //
+				.doesNotHaveJsonPathValue("@.open");
+	}
+}