diff --git a/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarURLConnection.java b/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarURLConnection.java
index 45da271918d..fcefabb025b 100644
--- a/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarURLConnection.java
+++ b/spring-boot-tools/spring-boot-loader/src/main/java/org/springframework/boot/loader/jar/JarURLConnection.java
@@ -59,6 +59,8 @@ class JarURLConnection extends java.net.JarURLConnection {
 
 	private static final JarEntryName EMPTY_JAR_ENTRY_NAME = new JarEntryName("");
 
+	private static final String FILE_COLON_DOUBLE_SLASH = "file://";
+
 	private static ThreadLocal<Boolean> useFastExceptions = new ThreadLocal<Boolean>();
 
 	private final JarFile jarFile;
@@ -73,7 +75,8 @@ class JarURLConnection extends java.net.JarURLConnection {
 		// What we pass to super is ultimately ignored
 		super(EMPTY_JAR_URL);
 		this.url = url;
-		String spec = url.getFile().substring(jarFile.getUrl().getFile().length());
+		String spec = getNormalizedFile(url)
+				.substring(jarFile.getUrl().getFile().length());
 		int separator;
 		while ((separator = spec.indexOf(SEPARATOR)) > 0) {
 			jarFile = getNestedJarFile(jarFile, spec.substring(0, separator));
@@ -83,6 +86,13 @@ class JarURLConnection extends java.net.JarURLConnection {
 		this.jarEntryName = getJarEntryName(spec);
 	}
 
+	private String getNormalizedFile(URL url) {
+		if (!url.getFile().startsWith(FILE_COLON_DOUBLE_SLASH)) {
+			return url.getFile();
+		}
+		return "file:" + url.getFile().substring(FILE_COLON_DOUBLE_SLASH.length());
+	}
+
 	private JarFile getNestedJarFile(JarFile jarFile, String name) throws IOException {
 		JarEntry jarEntry = jarFile.getJarEntry(name);
 		if (jarEntry == null) {
diff --git a/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/jar/JarFileTests.java b/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/jar/JarFileTests.java
index 9386b7877a2..cc6eb8f2e2d 100644
--- a/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/jar/JarFileTests.java
+++ b/spring-boot-tools/spring-boot-loader/src/test/java/org/springframework/boot/loader/jar/JarFileTests.java
@@ -313,8 +313,18 @@ public class JarFileTests {
 
 	@Test
 	public void createNonNestedUrlFromString() throws Exception {
+		nonNestedJarFileFromString(
+				"jar:file:" + this.rootJarFile.getAbsolutePath() + "!/2.dat");
+	}
+
+	@Test
+	public void createNonNestedUrlFromStringWithDoubleSlash() throws Exception {
+		nonNestedJarFileFromString(
+				"jar:file://" + this.rootJarFile.getAbsolutePath() + "!/2.dat");
+	}
+
+	private void nonNestedJarFileFromString(String spec) throws Exception {
 		JarFile.registerUrlProtocolHandler();
-		String spec = "jar:" + this.rootJarFile.toURI() + "!/2.dat";
 		URL url = new URL(spec);
 		assertThat(url.toString()).isEqualTo(spec);
 		InputStream inputStream = url.openStream();