diff --git a/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/JarLauncher.java b/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/JarLauncher.java
index ecabbc1fdf1..3a6d1339ca1 100644
--- a/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/JarLauncher.java
+++ b/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/JarLauncher.java
@@ -38,11 +38,7 @@ public class JarLauncher extends ExecutableArchiveLauncher {
 
 	@Override
 	protected boolean isIncludedOnClassPath(Archive.Entry entry) {
-		String name = entry.name();
-		if (entry.isDirectory()) {
-			return name.equals("BOOT-INF/classes/");
-		}
-		return name.startsWith("BOOT-INF/lib/");
+		return isLibraryFileOrClassesDirectory(entry);
 	}
 
 	@Override
@@ -50,6 +46,14 @@ public class JarLauncher extends ExecutableArchiveLauncher {
 		return "BOOT-INF/";
 	}
 
+	static boolean isLibraryFileOrClassesDirectory(Archive.Entry entry) {
+		String name = entry.name();
+		if (entry.isDirectory()) {
+			return name.equals("BOOT-INF/classes/");
+		}
+		return name.startsWith("BOOT-INF/lib/");
+	}
+
 	public static void main(String[] args) throws Exception {
 		new JarLauncher().launch(args);
 	}
diff --git a/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/PropertiesLauncher.java b/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/PropertiesLauncher.java
index 8b88484df48..efa9d80c0b3 100644
--- a/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/PropertiesLauncher.java
+++ b/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/PropertiesLauncher.java
@@ -140,7 +140,11 @@ public class PropertiesLauncher extends Launcher {
 	private final Properties properties = new Properties();
 
 	public PropertiesLauncher() throws Exception {
-		this.archive = Archive.create(Launcher.class);
+		this(Archive.create(Launcher.class));
+	}
+
+	PropertiesLauncher(Archive archive) throws Exception {
+		this.archive = archive;
 		this.homeDirectory = getHomeDirectory();
 		initializeProperties();
 		this.paths = getPaths();
@@ -464,6 +468,8 @@ public class PropertiesLauncher extends Launcher {
 			path = cleanupPath(handleUrl(path));
 			urls.addAll(getClassPathUrlsForPath(path));
 		}
+		urls.addAll(getClassPathUrlsForRoot());
+		debug.log("Using class path URLs %s", urls);
 		return urls;
 	}
 
@@ -531,6 +537,11 @@ public class PropertiesLauncher extends Launcher {
 		}
 	}
 
+	private Set<URL> getClassPathUrlsForRoot() throws IOException {
+		debug.log("Adding classpath entries from root archive %s", this.archive);
+		return this.archive.getClassPathUrls(JarLauncher::isLibraryFileOrClassesDirectory);
+	}
+
 	private Predicate<Entry> includeByPrefix(String prefix) {
 		return (entry) -> (entry.isDirectory() && entry.name().equals(prefix))
 				|| (isArchive(entry) && entry.name().startsWith(prefix));
diff --git a/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/WarLauncher.java b/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/WarLauncher.java
index a74e63c4abc..38318ba222c 100644
--- a/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/WarLauncher.java
+++ b/spring-boot-project/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/launch/WarLauncher.java
@@ -37,11 +37,7 @@ public class WarLauncher extends ExecutableArchiveLauncher {
 
 	@Override
 	public boolean isIncludedOnClassPath(Archive.Entry entry) {
-		String name = entry.name();
-		if (entry.isDirectory()) {
-			return name.equals("WEB-INF/classes/");
-		}
-		return name.startsWith("WEB-INF/lib/") || name.startsWith("WEB-INF/lib-provided/");
+		return isLibraryFileOrClassesDirectory(entry);
 	}
 
 	@Override
@@ -49,6 +45,14 @@ public class WarLauncher extends ExecutableArchiveLauncher {
 		return "WEB-INF/";
 	}
 
+	static boolean isLibraryFileOrClassesDirectory(Archive.Entry entry) {
+		String name = entry.name();
+		if (entry.isDirectory()) {
+			return name.equals("WEB-INF/classes/");
+		}
+		return name.startsWith("WEB-INF/lib/") || name.startsWith("WEB-INF/lib-provided/");
+	}
+
 	public static void main(String[] args) throws Exception {
 		new WarLauncher().launch(args);
 	}
diff --git a/spring-boot-project/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/launch/PropertiesLauncherTests.java b/spring-boot-project/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/launch/PropertiesLauncherTests.java
index 6e41ed6f912..9bac00e9e74 100644
--- a/spring-boot-project/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/launch/PropertiesLauncherTests.java
+++ b/spring-boot-project/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/launch/PropertiesLauncherTests.java
@@ -18,6 +18,7 @@ package org.springframework.boot.loader.launch;
 
 import java.io.File;
 import java.io.FileOutputStream;
+import java.io.InputStream;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.time.Duration;
@@ -26,7 +27,10 @@ import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.jar.Attributes;
+import java.util.jar.JarFile;
+import java.util.jar.JarOutputStream;
 import java.util.jar.Manifest;
+import java.util.zip.ZipEntry;
 
 import org.assertj.core.api.Condition;
 import org.awaitility.Awaitility;
@@ -309,8 +313,8 @@ class PropertiesLauncherTests {
 		assertThat(Arrays.asList(this.launcher.getArgs("bar"))).hasToString("[foo, bar]");
 	}
 
-	@SuppressWarnings("unchecked")
 	@Test
+	@SuppressWarnings("unchecked")
 	void testLoadPathCustomizedUsingManifest() throws Exception {
 		System.setProperty("loader.home", this.tempDir.getAbsolutePath());
 		Manifest manifest = new Manifest();
@@ -364,6 +368,29 @@ class PropertiesLauncherTests {
 		assertThat(bytes).isNotEmpty();
 	}
 
+	@Test // gh-37992
+	void classPathWithoutLoaderPathDefaultsToJarLauncherIncludes() throws Exception {
+		File file = new File(this.tempDir, "test.jar");
+		try (JarOutputStream out = new JarOutputStream(new FileOutputStream(file))) {
+			try (JarFile in = new JarFile(new File("src/test/resources/jars/app.jar"))) {
+				out.putNextEntry(new ZipEntry("BOOT-INF/"));
+				out.putNextEntry(new ZipEntry("BOOT-INF/classes/"));
+				out.putNextEntry(new ZipEntry("BOOT-INF/classes/demo/"));
+				out.putNextEntry(new ZipEntry("BOOT-INF/classes/demo/Application.class"));
+				try (InputStream classIn = in.getInputStream(in.getEntry("demo/Application.class"))) {
+					classIn.transferTo(out);
+				}
+				out.closeEntry();
+			}
+		}
+		Archive archive = new JarFileArchive(file);
+		System.setProperty("loader.main", "demo.Application");
+		this.launcher = new PropertiesLauncher(archive);
+		this.launcher.launch(new String[0]);
+		waitFor("Hello World");
+
+	}
+
 	private void waitFor(String value) {
 		Awaitility.waitAtMost(Duration.ofSeconds(5)).until(this.output::toString, containsString(value));
 	}