diff --git a/spring-modulith-core/src/main/java/org/springframework/modulith/core/ApplicationModules.java b/spring-modulith-core/src/main/java/org/springframework/modulith/core/ApplicationModules.java
index ecfbe96e..9220b56e 100644
--- a/spring-modulith-core/src/main/java/org/springframework/modulith/core/ApplicationModules.java
+++ b/spring-modulith-core/src/main/java/org/springframework/modulith/core/ApplicationModules.java
@@ -340,13 +340,16 @@ public class ApplicationModules implements Iterable<ApplicationModule> {
 	 * modules.
 	 *
 	 * @param className must not be {@literal null} or empty.
-	 * @return
 	 */
 	public boolean withinRootPackages(String className) {
 
 		Assert.hasText(className, "Class name must not be null or empty!");
 
-		return rootPackages.stream().anyMatch(it -> it.contains(className));
+		var candidate = PackageName.ofType(className);
+
+		return rootPackages.stream()
+				.map(JavaPackage::getPackageName)
+				.anyMatch(candidate::equals);
 	}
 
 	/**
diff --git a/spring-modulith-core/src/main/java/org/springframework/modulith/core/JavaPackage.java b/spring-modulith-core/src/main/java/org/springframework/modulith/core/JavaPackage.java
index 5f19c989..b4cc818d 100644
--- a/spring-modulith-core/src/main/java/org/springframework/modulith/core/JavaPackage.java
+++ b/spring-modulith-core/src/main/java/org/springframework/modulith/core/JavaPackage.java
@@ -293,9 +293,9 @@ public class JavaPackage implements DescribedIterable<JavaClass>, Comparable<Jav
 	 * Returns the name of the package.
 	 *
 	 * @return will never be {@literal null}.
-	 * @since 1.3
+	 * @since 1.4, package protected since 1.3
 	 */
-	PackageName getPackageName() {
+	public PackageName getPackageName() {
 		return name;
 	}
 
diff --git a/spring-modulith-core/src/main/java/org/springframework/modulith/core/PackageName.java b/spring-modulith-core/src/main/java/org/springframework/modulith/core/PackageName.java
index 53843d41..c62ca790 100644
--- a/spring-modulith-core/src/main/java/org/springframework/modulith/core/PackageName.java
+++ b/spring-modulith-core/src/main/java/org/springframework/modulith/core/PackageName.java
@@ -30,9 +30,9 @@ import org.springframework.util.ClassUtils;
  * last.
  *
  * @author Oliver Drotbohm
- * @since 1.2
+ * @since 1.4, previously package private since 1.2
  */
-class PackageName implements Comparable<PackageName> {
+public class PackageName implements Comparable<PackageName> {
 
 	private static final Map<String, PackageName> PACKAGE_NAMES = new HashMap<>();
 
@@ -68,8 +68,9 @@ class PackageName implements Comparable<PackageName> {
 	 *
 	 * @param fullyQualifiedName must not be {@literal null} or empty.
 	 * @return will never be {@literal null}.
+	 * @since 1.4
 	 */
-	static PackageName ofType(String fullyQualifiedName) {
+	public static PackageName ofType(String fullyQualifiedName) {
 
 		Assert.notNull(fullyQualifiedName, "Type name must not be null!");
 
@@ -191,8 +192,9 @@ class PackageName implements Comparable<PackageName> {
 	 * sub-package of it.
 	 *
 	 * @param reference must not be {@literal null}.
+	 * @since 1.4
 	 */
-	boolean contains(PackageName reference) {
+	public boolean contains(PackageName reference) {
 
 		Assert.notNull(reference, "Reference package name must not be null!");
 
diff --git a/spring-modulith-test/src/main/java/org/springframework/modulith/test/ModuleTestExecution.java b/spring-modulith-test/src/main/java/org/springframework/modulith/test/ModuleTestExecution.java
index 828f7f9c..b71a1333 100644
--- a/spring-modulith-test/src/main/java/org/springframework/modulith/test/ModuleTestExecution.java
+++ b/spring-modulith-test/src/main/java/org/springframework/modulith/test/ModuleTestExecution.java
@@ -36,6 +36,7 @@ import org.springframework.modulith.core.ApplicationModule;
 import org.springframework.modulith.core.ApplicationModules;
 import org.springframework.modulith.core.ApplicationModulesFactory;
 import org.springframework.modulith.core.JavaPackage;
+import org.springframework.modulith.core.PackageName;
 import org.springframework.modulith.test.ApplicationModuleTest.BootstrapMode;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
@@ -134,8 +135,7 @@ public class ModuleTestExecution implements Iterable<ApplicationModule> {
 
 	public boolean includes(String className) {
 
-		var result = modules.withinRootPackages(className) //
-				|| basePackages.get().stream().anyMatch(it -> it.contains(className));
+		var result = isLocatedInRootPackageOrContainedInBasePackages(className);
 
 		if (result) {
 			LOGGER.trace("Including class {}.", className);
@@ -239,6 +239,17 @@ public class ModuleTestExecution implements Iterable<ApplicationModule> {
 		return Objects.hash(key);
 	}
 
+	private boolean isLocatedInRootPackageOrContainedInBasePackages(String className) {
+
+		if (modules.withinRootPackages(className)) {
+			return true;
+		}
+
+		var candidate = PackageName.ofType(className);
+
+		return basePackages.get().stream().map(JavaPackage::getPackageName).anyMatch(it -> it.contains(candidate));
+	}
+
 	private static Stream<ApplicationModule> getExtraModules(ApplicationModuleTest annotation,
 			ApplicationModules modules) {