diff --git a/independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/classloading/QuarkusClassLoader.java b/independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/classloading/QuarkusClassLoader.java
index 35dfd19b162cb..440a8d6f5f238 100644
--- a/independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/classloading/QuarkusClassLoader.java
+++ b/independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/classloading/QuarkusClassLoader.java
@@ -406,7 +406,12 @@ public InputStream getResourceAsStream(String unsanitisedName) {
         if (name.endsWith(".class")) {
             ClassPathElement[] providers = state.loadableResources.get(name);
             if (providers != null) {
-                return new ByteArrayInputStream(providers[0].getResource(name).getData());
+                final ClassPathResource resource = providers[0].getResource(name);
+                if (resource == null) {
+                    throw new IllegalStateException(providers[0] + " from " + getName() + " (closed=" + this.isClosed()
+                            + ") was expected to provide " + name + " but failed");
+                }
+                return new ByteArrayInputStream(resource.getData());
             }
         } else {
             for (ClassPathElement i : elements) {