diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LockBasedStorageManager.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LockBasedStorageManager.java
index 18c583d88c3..df0a51889a6 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LockBasedStorageManager.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/LockBasedStorageManager.java
@@ -19,7 +19,13 @@ package org.jetbrains.jet.lang.resolve.lazy;
 import com.intellij.openapi.util.Computable;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.jet.lang.diagnostics.Diagnostic;
+import org.jetbrains.jet.lang.resolve.BindingContext;
+import org.jetbrains.jet.lang.resolve.BindingTrace;
+import org.jetbrains.jet.util.slicedmap.ReadOnlySlice;
+import org.jetbrains.jet.util.slicedmap.WritableSlice;
 
+import java.util.Collection;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 
@@ -44,6 +50,14 @@ public class LockBasedStorageManager implements StorageManager {
         return new LockBasedLazyValue<T>(lock, computable);
     }
 
+    @NotNull
+    @Override
+    public BindingTrace createSafeTrace(@NotNull BindingTrace originalTrace) {
+        // It seems safe to have a separate lock for traces:
+        // no other locks will be acquired inside the trace operations
+        return new LockProtectedTrace(lock, originalTrace);
+    }
+
     private static class LockBasedLazyValue<T> implements LazyValue<T> {
         private final Object lock;
         private final Computable<T> computable;
@@ -74,4 +88,58 @@ public class LockBasedStorageManager implements StorageManager {
             }
         }
     }
+
+    private static class LockProtectedTrace implements BindingTrace {
+        private final Object lock;
+        private final BindingTrace trace;
+
+        public LockProtectedTrace(@NotNull Object lock, @NotNull BindingTrace trace) {
+            this.lock = lock;
+            this.trace = trace;
+        }
+
+        @Override
+        public BindingContext getBindingContext() {
+            synchronized (lock) {
+                return trace.getBindingContext();
+            }
+        }
+
+        @Override
+        public <K, V> void record(WritableSlice<K, V> slice, K key, V value) {
+            synchronized (lock) {
+                trace.record(slice, key, value);
+            }
+        }
+
+        @Override
+        public <K> void record(WritableSlice<K, Boolean> slice, K key) {
+            synchronized (lock) {
+                trace.record(slice, key);
+            }
+        }
+
+        @Override
+        @Nullable
+        public <K, V> V get(ReadOnlySlice<K, V> slice, K key) {
+            synchronized (lock) {
+                return trace.get(slice, key);
+            }
+        }
+
+        @Override
+        @NotNull
+        public <K, V> Collection<K> getKeys(WritableSlice<K, V> slice) {
+            synchronized (lock) {
+                return trace.getKeys(slice);
+            }
+        }
+
+        @Override
+        public void report(@NotNull Diagnostic diagnostic) {
+            synchronized (lock) {
+                trace.report(diagnostic);
+            }
+        }
+    }
 }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/ResolveSession.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/ResolveSession.java
index 97a27ac3acf..1dfbfd7fd69 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/ResolveSession.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/ResolveSession.java
@@ -107,7 +107,7 @@ public class ResolveSession {
         this.storageManager = storageManager;
         this.classifierAliases = classifierAliases;
         this.specialClasses = specialClasses;
-        this.trace = new ObservableBindingTrace(delegationTrace);
+        this.trace = storageManager.createSafeTrace(delegationTrace);
         this.injector = new InjectorForLazyResolve(project, this, trace, moduleConfiguration);
         this.module = rootDescriptor;
         this.moduleConfiguration = moduleConfiguration;
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/StorageManager.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/StorageManager.java
index 893a65c9ebd..6f553db0ecd 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/StorageManager.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/lazy/StorageManager.java
@@ -18,6 +18,7 @@ package org.jetbrains.jet.lang.resolve.lazy;
 
 import com.intellij.openapi.util.Computable;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.jet.lang.resolve.BindingTrace;
 
 import java.util.concurrent.ConcurrentMap;
 
@@ -27,4 +28,7 @@ public interface StorageManager {
 
     @NotNull
     <T> LazyValue<T> createLazyValue(@NotNull Computable<T> computable);
+
+    @NotNull
+    BindingTrace createSafeTrace(@NotNull BindingTrace originalTrace);
 }