diff --git a/loader/spring-boot-jarmode-tools/build.gradle b/loader/spring-boot-jarmode-tools/build.gradle
index 31a1d6ed72e..839816ebd65 100644
--- a/loader/spring-boot-jarmode-tools/build.gradle
+++ b/loader/spring-boot-jarmode-tools/build.gradle
@@ -30,3 +30,7 @@ dependencies {
 	testImplementation("org.mockito:mockito-core")
 	testImplementation("org.mockito:mockito-junit-jupiter")
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}
diff --git a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/AbstractJarModeTests.java b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/AbstractJarModeTests.java
index 12fd0c638c8..03a405aac2c 100644
--- a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/AbstractJarModeTests.java
+++ b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/AbstractJarModeTests.java
@@ -35,6 +35,7 @@ import java.util.jar.Manifest;
 import java.util.stream.Stream;
 import java.util.zip.ZipEntry;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.io.TempDir;
 
 import org.springframework.util.Assert;
@@ -51,6 +52,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 abstract class AbstractJarModeTests {
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	File tempDir;
 
 	Manifest createManifest(String... entries) {
@@ -74,8 +76,8 @@ abstract class AbstractJarModeTests {
 		return createArchive(manifest, null, null, null, entries);
 	}
 
-	File createArchive(Manifest manifest, Instant creationTime, Instant lastModifiedTime, Instant lastAccessTime,
-			String... entries) throws IOException {
+	File createArchive(Manifest manifest, @Nullable Instant creationTime, @Nullable Instant lastModifiedTime,
+			@Nullable Instant lastAccessTime, String... entries) throws IOException {
 		Assert.state(entries.length % 2 == 0, "Entries must be key value pairs");
 		File file = new File(this.tempDir, "test.jar");
 		try (JarOutputStream jar = new JarOutputStream(new FileOutputStream(file), manifest)) {
diff --git a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/CommandTests.java b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/CommandTests.java
index 46fec0e0720..273b6a86692 100644
--- a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/CommandTests.java
+++ b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/CommandTests.java
@@ -23,6 +23,7 @@ import java.util.List;
 import java.util.Map;
 
 import org.assertj.core.api.InstanceOfAssertFactories;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.jarmode.tools.Command.Option;
@@ -165,9 +166,9 @@ class CommandTests {
 
 	static class TestCommand extends Command {
 
-		private Map<Option, String> runOptions;
+		private @Nullable Map<Option, @Nullable String> runOptions;
 
-		private List<String> runParameters;
+		private @Nullable List<String> runParameters;
 
 		TestCommand(String name, Option... options) {
 			this(name, "test", Options.of(options), Parameters.none());
@@ -178,16 +179,16 @@ class CommandTests {
 		}
 
 		@Override
-		protected void run(PrintStream out, Map<Option, String> options, List<String> parameters) {
+		protected void run(PrintStream out, Map<Option, @Nullable String> options, List<String> parameters) {
 			this.runOptions = options;
 			this.runParameters = parameters;
 		}
 
-		Map<Option, String> getRunOptions() {
+		@Nullable Map<Option, @Nullable String> getRunOptions() {
 			return this.runOptions;
 		}
 
-		List<String> getRunParameters() {
+		@Nullable List<String> getRunParameters() {
 			return this.runParameters;
 		}
 
diff --git a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ContextTests.java b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ContextTests.java
index fc104f84b51..1e12f7dbdb2 100644
--- a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ContextTests.java
+++ b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ContextTests.java
@@ -34,9 +34,11 @@ import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 class ContextTests {
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	File temp;
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenSourceIsNullThrowsException() {
 		assertThatIllegalStateException().isThrownBy(() -> new Context(null, this.temp))
 			.withMessage("Unable to find source archive");
diff --git a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ExtractCommandTests.java b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ExtractCommandTests.java
index fd2c9d7e146..c7d0187e9b0 100644
--- a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ExtractCommandTests.java
+++ b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ExtractCommandTests.java
@@ -297,7 +297,7 @@ class ExtractCommandTests extends AbstractJarModeTests {
 
 		@Test
 		void runWithJarFileThatWouldWriteEntriesOutsideDestinationFails() throws Exception {
-			File file = createArchive("e/../../e.jar", null);
+			File file = createArchive("e/../../e.jar", "");
 			assertThatIllegalStateException().isThrownBy(() -> run(file, "--launcher"))
 				.withMessageContaining("Entry 'e/../../e.jar' would be written");
 		}
diff --git a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ExtractLayersCommandTests.java b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ExtractLayersCommandTests.java
index 3979dac0522..b15eaace46c 100644
--- a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ExtractLayersCommandTests.java
+++ b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ExtractLayersCommandTests.java
@@ -69,9 +69,11 @@ class ExtractLayersCommandTests {
 	private static final FileTime LAST_ACCESS_TIME = FileTime.from(NOW.minus(1, ChronoUnit.DAYS));
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	File temp;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private Context context;
 
 	private File jarFile;
diff --git a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/HelpCommandTests.java b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/HelpCommandTests.java
index 0d99200b3da..77e6991e06f 100644
--- a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/HelpCommandTests.java
+++ b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/HelpCommandTests.java
@@ -40,6 +40,7 @@ class HelpCommandTests {
 	private TestPrintStream out;
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	Path temp;
 
 	@BeforeEach
diff --git a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/IndexedJarStructureTests.java b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/IndexedJarStructureTests.java
index 925b65628eb..0585b824254 100644
--- a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/IndexedJarStructureTests.java
+++ b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/IndexedJarStructureTests.java
@@ -47,6 +47,7 @@ class IndexedJarStructureTests {
 	void shouldResolveLibraryEntry() throws IOException {
 		IndexedJarStructure structure = createStructure();
 		Entry entry = structure.resolve("BOOT-INF/lib/spring-webmvc-6.1.4.jar");
+		assertThat(entry).isNotNull();
 		assertThat(entry.location()).isEqualTo("spring-webmvc-6.1.4.jar");
 		assertThat(entry.originalLocation()).isEqualTo("BOOT-INF/lib/spring-webmvc-6.1.4.jar");
 		assertThat(entry.type()).isEqualTo(Type.LIBRARY);
@@ -56,6 +57,7 @@ class IndexedJarStructureTests {
 	void shouldResolveApplicationEntry() throws IOException {
 		IndexedJarStructure structure = createStructure();
 		Entry entry = structure.resolve("BOOT-INF/classes/application.properties");
+		assertThat(entry).isNotNull();
 		assertThat(entry.location()).isEqualTo("application.properties");
 		assertThat(entry.originalLocation()).isEqualTo("BOOT-INF/classes/application.properties");
 		assertThat(entry.type()).isEqualTo(Type.APPLICATION_CLASS_OR_RESOURCE);
@@ -65,6 +67,7 @@ class IndexedJarStructureTests {
 	void shouldResolveLoaderEntry() throws IOException {
 		IndexedJarStructure structure = createStructure();
 		Entry entry = structure.resolve("org/springframework/boot/loader/launch/JarLauncher");
+		assertThat(entry).isNotNull();
 		assertThat(entry.location()).isEqualTo("org/springframework/boot/loader/launch/JarLauncher");
 		assertThat(entry.originalLocation()).isEqualTo("org/springframework/boot/loader/launch/JarLauncher");
 		assertThat(entry.type()).isEqualTo(Type.LOADER);
diff --git a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/IndexedLayersTests.java b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/IndexedLayersTests.java
index c32f0de73ad..82a49a5e905 100644
--- a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/IndexedLayersTests.java
+++ b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/IndexedLayersTests.java
@@ -42,6 +42,7 @@ import static org.mockito.Mockito.mock;
 class IndexedLayersTests {
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	File temp;
 
 	@Test
@@ -94,6 +95,7 @@ class IndexedLayersTests {
 		Context context = mock(Context.class);
 		given(context.getArchiveFile()).willReturn(createWarFile("test.war"));
 		IndexedLayers layers = IndexedLayers.get(context);
+		assertThat(layers).isNotNull();
 		assertThat(layers.getLayer(mockEntry("WEB-INF/lib/a.jar"))).isEqualTo("test");
 	}
 
diff --git a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/LayerToolsJarModeTests.java b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/LayerToolsJarModeTests.java
index 53a76ea6059..2fa8507ba6c 100644
--- a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/LayerToolsJarModeTests.java
+++ b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/LayerToolsJarModeTests.java
@@ -53,6 +53,7 @@ class LayerToolsJarModeTests {
 	private PrintStream systemOut;
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	File temp;
 
 	@BeforeEach
diff --git a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ListCommandTests.java b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ListCommandTests.java
index b37533c00d4..f890a772691 100644
--- a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ListCommandTests.java
+++ b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/ListCommandTests.java
@@ -48,9 +48,11 @@ import static org.mockito.BDDMockito.given;
 class ListCommandTests {
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	File temp;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private Context context;
 
 	private ListCommand command;
@@ -68,6 +70,7 @@ class ListCommandTests {
 	@Test
 	void listLayersShouldListLayers() {
 		Layers layers = IndexedLayers.get(this.context);
+		assertThat(layers).isNotNull();
 		this.command.printLayers(layers, this.out);
 		assertThat(this.out).hasSameContentAsResource("list-output-without-deprecation.txt");
 	}
diff --git a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/TestCommand.java b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/TestCommand.java
index f130d611276..531b0ec37bc 100644
--- a/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/TestCommand.java
+++ b/loader/spring-boot-jarmode-tools/src/test/java/org/springframework/boot/jarmode/tools/TestCommand.java
@@ -20,6 +20,8 @@ import java.io.PrintStream;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * @author Moritz Halbritter
  */
@@ -33,7 +35,7 @@ class TestCommand extends Command {
 	}
 
 	@Override
-	protected void run(PrintStream out, Map<Option, String> options, List<String> parameters) {
+	protected void run(PrintStream out, Map<Option, @Nullable String> options, List<String> parameters) {
 
 	}