diff --git a/extensions/vertx-core/runtime/src/main/java/io/quarkus/vertx/core/runtime/graal/JdkSubstitutions.java b/extensions/vertx-core/runtime/src/main/java/io/quarkus/vertx/core/runtime/graal/JdkSubstitutions.java
index 14afde0c96753..631f344c6b569 100644
--- a/extensions/vertx-core/runtime/src/main/java/io/quarkus/vertx/core/runtime/graal/JdkSubstitutions.java
+++ b/extensions/vertx-core/runtime/src/main/java/io/quarkus/vertx/core/runtime/graal/JdkSubstitutions.java
@@ -8,8 +8,10 @@
 import com.oracle.svm.core.annotate.Alias;
 import com.oracle.svm.core.annotate.Substitute;
 import com.oracle.svm.core.annotate.TargetClass;
+import com.oracle.svm.core.jdk.JDK11OrLater;
+import com.oracle.svm.core.jdk.JDK8OrEarlier;
 
-@TargetClass(className = "sun.misc.URLClassPath$Loader")
+@TargetClass(className = "sun.misc.URLClassPath$Loader", onlyWith = JDK8OrEarlier.class)
 final class Target_sun_misc_URLClassPath$Loader {
 
     @Alias
@@ -17,7 +19,15 @@ final class Target_sun_misc_URLClassPath$Loader {
     }
 }
 
-@TargetClass(className = "sun.misc.URLClassPath$FileLoader")
+@TargetClass(className = "jdk.internal.loader.URLClassPath$Loader", onlyWith = JDK11OrLater.class)
+final class Target_jdk_internal_loader_URLClassPath$Loader {
+
+    @Alias
+    public Target_jdk_internal_loader_URLClassPath$Loader(URL url) {
+    }
+}
+
+@TargetClass(className = "sun.misc.URLClassPath$FileLoader", onlyWith = JDK8OrEarlier.class)
 final class Target_sun_misc_URLClassPath$FileLoader {
 
     @Alias
@@ -25,7 +35,15 @@ final class Target_sun_misc_URLClassPath$FileLoader {
     }
 }
 
-@TargetClass(className = "sun.misc.URLClassPath")
+@TargetClass(className = "jdk.internal.loader.URLClassPath$FileLoader")
+final class Target_jdk_internal_loader_URLClassPath$FileLoader {
+
+    @Alias
+    public Target_jdk_internal_loader_URLClassPath$FileLoader(URL url) throws IOException {
+    }
+}
+
+@TargetClass(className = "sun.misc.URLClassPath", onlyWith = JDK8OrEarlier.class)
 final class Target_sun_misc_URLClassPath {
 
     @Substitute
@@ -51,6 +69,28 @@ private int[] getLookupCache(String name) {
     }
 }
 
+@TargetClass(className = "jdk.internal.loader.URLClassPath", onlyWith = JDK11OrLater.class)
+final class Target_jdk_internal_loader_URLClassPath {
+
+    @Substitute
+    private Target_jdk_internal_loader_URLClassPath$Loader getLoader(final URL url) throws IOException {
+        String file = url.getFile();
+        if (file != null && file.endsWith("/")) {
+            if ("file".equals(url.getProtocol())) {
+                return (Target_jdk_internal_loader_URLClassPath$Loader) (Object) new Target_jdk_internal_loader_URLClassPath$FileLoader(
+                        url);
+            } else {
+                return new Target_jdk_internal_loader_URLClassPath$Loader(url);
+            }
+        } else {
+            // that must be wrong, but JarLoader is deleted by SVM
+            return (Target_jdk_internal_loader_URLClassPath$Loader) (Object) new Target_jdk_internal_loader_URLClassPath$FileLoader(
+                    url);
+        }
+    }
+
+}
+
 @TargetClass(className = "sun.nio.ch.DatagramChannelImpl", onlyWith = GraalVersion19_0.class)
 final class Target_sun_nio_ch_DatagramChannelImpl {