diff --git a/start-site/src/main/java/io/spring/start/site/extension/description/DescriptionProjectGenerationConfiguration.java b/start-site/src/main/java/io/spring/start/site/extension/description/DescriptionProjectGenerationConfiguration.java
index a62496ce06..2541cd5988 100644
--- a/start-site/src/main/java/io/spring/start/site/extension/description/DescriptionProjectGenerationConfiguration.java
+++ b/start-site/src/main/java/io/spring/start/site/extension/description/DescriptionProjectGenerationConfiguration.java
@@ -37,4 +37,10 @@ public InvalidJvmVersionHelpDocumentCustomizer invalidJvmVersionHelpDocumentCust
 		return new InvalidJvmVersionHelpDocumentCustomizer(diff, description);
 	}
 
+	@Bean
+	public InvalidPackageNameHelpDocumentCustomizer invalidPackageNameHelpDocumentCustomizer(
+			ProjectDescriptionDiff diff, ProjectDescription description) {
+		return new InvalidPackageNameHelpDocumentCustomizer(diff, description);
+	}
+
 }
diff --git a/start-site/src/main/java/io/spring/start/site/extension/description/InvalidPackageNameHelpDocumentCustomizer.java b/start-site/src/main/java/io/spring/start/site/extension/description/InvalidPackageNameHelpDocumentCustomizer.java
new file mode 100644
index 0000000000..6be214b3f7
--- /dev/null
+++ b/start-site/src/main/java/io/spring/start/site/extension/description/InvalidPackageNameHelpDocumentCustomizer.java
@@ -0,0 +1,50 @@
+/*
+ * Copyright 2012-2020 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
+ *
+ *      https://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 io.spring.start.site.extension.description;
+
+import io.spring.initializr.generator.project.ProjectDescription;
+import io.spring.initializr.generator.project.ProjectDescriptionDiff;
+import io.spring.initializr.generator.spring.documentation.HelpDocument;
+import io.spring.initializr.generator.spring.documentation.HelpDocumentCustomizer;
+
+/**
+ * A {@link HelpDocumentCustomizer} that adds a warning when the package name was changed.
+ *
+ * @author Stephane Nicoll
+ */
+public class InvalidPackageNameHelpDocumentCustomizer implements HelpDocumentCustomizer {
+
+	private final ProjectDescriptionDiff diff;
+
+	private final ProjectDescription description;
+
+	public InvalidPackageNameHelpDocumentCustomizer(ProjectDescriptionDiff diff, ProjectDescription description) {
+		this.diff = diff;
+		this.description = description;
+	}
+
+	@Override
+	public void customize(HelpDocument document) {
+		this.diff.ifPackageNameChanged(this.description,
+				(original, current) -> document.getWarnings()
+						.addItem(String.format(
+								"The original package name '%s' is invalid and this project uses '%s' instead.",
+								original, current)));
+
+	}
+
+}
diff --git a/start-site/src/test/java/io/spring/start/site/extension/description/InvalidPackageNameHelpDocumentCustomizerTests.java b/start-site/src/test/java/io/spring/start/site/extension/description/InvalidPackageNameHelpDocumentCustomizerTests.java
new file mode 100644
index 0000000000..036b63233d
--- /dev/null
+++ b/start-site/src/test/java/io/spring/start/site/extension/description/InvalidPackageNameHelpDocumentCustomizerTests.java
@@ -0,0 +1,50 @@
+/*
+ * Copyright 2012-2020 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
+ *
+ *      https://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 io.spring.start.site.extension.description;
+
+import io.spring.initializr.generator.test.io.TextAssert;
+import io.spring.initializr.generator.test.project.ProjectStructure;
+import io.spring.initializr.web.project.ProjectRequest;
+import io.spring.start.site.extension.AbstractExtensionTests;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests for {@link InvalidPackageNameHelpDocumentCustomizer}.
+ *
+ * @author Stephane Nicoll
+ */
+class InvalidPackageNameHelpDocumentCustomizerTests extends AbstractExtensionTests {
+
+	@Test
+	void warningAddedWithInvalidPackageName() {
+		assertHelpDocument("com.my-invalid-package").lines().containsSubsequence("# Read Me First",
+				"* The original package name 'com.my-invalid-package' is invalid and this project uses 'com.myinvalidpackage' instead.");
+	}
+
+	@Test
+	void warningNotAddedWithValidPackageName() {
+		assertHelpDocument("com.example.valid").doesNotContain("# Read Me First");
+	}
+
+	private TextAssert assertHelpDocument(String packageName) {
+		ProjectRequest request = createProjectRequest("web");
+		request.setPackageName(packageName);
+		ProjectStructure project = generateProject(request);
+		return new TextAssert(project.getProjectDirectory().resolve("HELP.md"));
+	}
+
+}