diff --git a/teavm-classlib/src/main/java/org/teavm/classlibgen/ClasslibTestGenerator.java b/teavm-classlib/src/main/java/org/teavm/classlibgen/ClasslibTestGenerator.java
index 228b81642..290ec68ff 100644
--- a/teavm-classlib/src/main/java/org/teavm/classlibgen/ClasslibTestGenerator.java
+++ b/teavm-classlib/src/main/java/org/teavm/classlibgen/ClasslibTestGenerator.java
@@ -2,10 +2,7 @@ package org.teavm.classlibgen;
 
 import java.io.IOException;
 import java.io.InputStream;
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import org.apache.commons.io.IOUtils;
 import org.teavm.codegen.DefaultAliasProvider;
 import org.teavm.codegen.DefaultNamingStrategy;
@@ -51,9 +48,7 @@ public class ClasslibTestGenerator {
         }
         dependencyChecker.checkDependencies();
         dependencyChecker.cutUnachievableClasses();
-        for (String className : dependencyChecker.getAchievableClasses()) {
-            decompileClass(className);
-        }
+        decompileClasses(dependencyChecker.getAchievableClasses());
         renderHead();
         ClassLoader classLoader = ClasslibTestGenerator.class.getClassLoader();
         try (InputStream input = classLoader.getResourceAsStream("org/teavm/classlib/junit-support.js")) {
@@ -69,10 +64,11 @@ public class ClasslibTestGenerator {
         renderFoot();
     }
 
-    private static void decompileClass(String className) {
-        ClassHolder cls = classSource.getClassHolder(className);
-        ClassNode clsNode = decompiler.decompile(cls);
-        renderer.render(clsNode);
+    private static void decompileClasses(Collection<String> classNames) {
+        List<ClassNode> clsNodes = decompiler.decompile(classNames);
+        for (ClassNode clsNode : clsNodes) {
+            renderer.render(clsNode);
+        }
     }
 
     private static void renderHead() {
diff --git a/teavm-core/src/main/java/org/teavm/codegen/ConcurrentCachedMapper.java b/teavm-core/src/main/java/org/teavm/codegen/ConcurrentCachedMapper.java
index 10f6e2dec..0d70cc45a 100644
--- a/teavm-core/src/main/java/org/teavm/codegen/ConcurrentCachedMapper.java
+++ b/teavm-core/src/main/java/org/teavm/codegen/ConcurrentCachedMapper.java
@@ -41,6 +41,7 @@ public class ConcurrentCachedMapper<T, R> implements Mapper<T, R> {
                 }
             } else {
                 CountDownLatch latch = oldWrapper.latch;
+                wrapper = oldWrapper;
                 try {
                     latch.await();
                 } catch (InterruptedException e) {
diff --git a/teavm-core/src/main/java/org/teavm/dependency/DependencyChecker.java b/teavm-core/src/main/java/org/teavm/dependency/DependencyChecker.java
index e767d6fca..a8f6c0db5 100644
--- a/teavm-core/src/main/java/org/teavm/dependency/DependencyChecker.java
+++ b/teavm-core/src/main/java/org/teavm/dependency/DependencyChecker.java
@@ -18,6 +18,7 @@ package org.teavm.dependency;
 import java.util.Collection;
 import java.util.HashSet;
 import java.util.concurrent.*;
+import java.util.concurrent.atomic.AtomicReference;
 import org.teavm.codegen.ConcurrentCachedMapper;
 import org.teavm.codegen.ConcurrentCachedMapper.KeyListener;
 import org.teavm.codegen.Mapper;
@@ -36,7 +37,7 @@ public class DependencyChecker {
     private ConcurrentCachedMapper<FieldReference, DependencyNode> fieldCache;
     private ConcurrentMap<String, Object> achievableClasses = new ConcurrentHashMap<>();
     private ConcurrentMap<String, Object> initializedClasses = new ConcurrentHashMap<>();
-    private volatile RuntimeException exceptionOccured;
+    private AtomicReference<RuntimeException> exceptionOccured = new AtomicReference<>();
 
     public DependencyChecker(ClassHolderSource classSource) {
         this(classSource, Runtime.getRuntime().availableProcessors());
@@ -99,21 +100,24 @@ public class DependencyChecker {
     }
 
     void schedule(final Runnable runnable) {
-        executor.execute(new Runnable() {
-            @Override
-            public void run() {
-                try {
-                    runnable.run();
-                } catch (RuntimeException e) {
-                    exceptionOccured = e;
-                    executor.shutdownNow();
+        try {
+            executor.execute(new Runnable() {
+                @Override public void run() {
+                    try {
+                        runnable.run();
+                    } catch (RuntimeException e) {
+                        exceptionOccured.compareAndSet(null, e);
+                        executor.shutdownNow();
+                    }
                 }
-            }
-        });
+            });
+        } catch (RejectedExecutionException e) {
+            throw exceptionOccured.get();
+        }
     }
 
     public void checkDependencies() {
-        exceptionOccured = null;
+        exceptionOccured.set(null);
         while (true) {
             try {
                 if (executor.getActiveCount() == 0 || executor.awaitTermination(1, TimeUnit.SECONDS)) {
@@ -124,8 +128,9 @@ public class DependencyChecker {
                 break;
             }
         }
-        if (exceptionOccured != null) {
-            throw exceptionOccured;
+        RuntimeException e = exceptionOccured.get();
+        if (e != null) {
+            throw exceptionOccured.get();
         }
     }
 
@@ -144,6 +149,9 @@ public class DependencyChecker {
                 break;
             }
             ClassHolder cls = classSource.getClassHolder(className);
+            if (cls == null) {
+                throw new RuntimeException("Class not found: " + className);
+            }
             if (cls.getMethod(clinitDesc) != null) {
                 attachMethodGraph(new MethodReference(className, clinitDesc));
             }
diff --git a/teavm-core/src/main/java/org/teavm/dependency/DependencyGraphBuilder.java b/teavm-core/src/main/java/org/teavm/dependency/DependencyGraphBuilder.java
index 4a2d758b8..297308b66 100644
--- a/teavm-core/src/main/java/org/teavm/dependency/DependencyGraphBuilder.java
+++ b/teavm-core/src/main/java/org/teavm/dependency/DependencyGraphBuilder.java
@@ -81,6 +81,9 @@ class DependencyGraphBuilder {
                 return;
             }
             MethodGraph targetGraph = checker.attachMethodGraph(methodRef);
+            if (targetGraph == null) {
+                throw new RuntimeException("Method not found: " + methodRef);
+            }
             DependencyNode[] targetParams = targetGraph.getVariableNodes();
             for (int i = 0; i < parameters.length; ++i) {
                 parameters[i].connect(targetParams[i]);
diff --git a/teavm-core/src/main/java/org/teavm/javascript/Decompiler.java b/teavm-core/src/main/java/org/teavm/javascript/Decompiler.java
index 98441fa70..988173763 100644
--- a/teavm-core/src/main/java/org/teavm/javascript/Decompiler.java
+++ b/teavm-core/src/main/java/org/teavm/javascript/Decompiler.java
@@ -62,6 +62,36 @@ public class Decompiler {
         }
     }
 
+    public List<ClassNode> decompile(Collection<String> classNames) {
+        List<String> sequence = new ArrayList<>();
+        Set<String> visited = new HashSet<>();
+        for (String className : classNames) {
+            orderClasses(className, visited, sequence);
+        }
+        List<ClassNode> result = new ArrayList<>();
+        for (String className : sequence) {
+            result.add(decompile(classSource.getClassHolder(className)));
+        }
+        return result;
+    }
+
+    private void orderClasses(String className, Set<String> visited, List<String> order) {
+        if (!visited.add(className)) {
+            return;
+        }
+        ClassHolder cls = classSource.getClassHolder(className);
+        if (cls == null) {
+            throw new IllegalArgumentException("Class not found: " + className);
+        }
+        if (cls.getParent() != null) {
+            orderClasses(cls.getParent(), visited, order);
+        }
+        for (String iface : cls.getInterfaces()) {
+            orderClasses(iface, visited, order);
+        }
+        order.add(className);
+    }
+
     public ClassNode decompile(ClassHolder cls) {
         ClassNode clsNode = new ClassNode(cls.getName(), cls.getParent());
         for (FieldHolder field : cls.getFields()) {