diff --git a/compiler/cli/src/org/jetbrains/jet/compiler/CompileEnvironment.java b/compiler/cli/src/org/jetbrains/jet/compiler/CompileEnvironment.java
index 1404bc105cf..9748cec343f 100644
--- a/compiler/cli/src/org/jetbrains/jet/compiler/CompileEnvironment.java
+++ b/compiler/cli/src/org/jetbrains/jet/compiler/CompileEnvironment.java
@@ -212,8 +212,8 @@ public class CompileEnvironment {
             method.setAccessible(true);
             method.invoke(null);
 
-            ArrayList<Module> answer = new ArrayList<Module>(AllModules.modules);
-            AllModules.modules.clear();
+            ArrayList<Module> answer = new ArrayList<Module>(AllModules.modules.get());
+            AllModules.modules.get().clear();
             return answer;
         }
         catch (Exception e) {
diff --git a/stdlib/ktSrc/modules/ModuleBuilder.kt b/stdlib/ktSrc/modules/ModuleBuilder.kt
index 487ef408f20..301e41930a8 100644
--- a/stdlib/ktSrc/modules/ModuleBuilder.kt
+++ b/stdlib/ktSrc/modules/ModuleBuilder.kt
@@ -6,7 +6,7 @@ import jet.modules.*
 fun module(name: String, callback:  ModuleBuilder.() -> Unit) {
     val builder = ModuleBuilder(name)
     builder.callback()
-    AllModules.modules?.add(builder)
+    AllModules.modules.sure().get()?.add(builder)
 }
 
 class SourcesBuilder(val parent: ModuleBuilder) {
diff --git a/stdlib/src/jet/modules/AllModules.java b/stdlib/src/jet/modules/AllModules.java
index d40c79c1d1f..a6580fe39ed 100644
--- a/stdlib/src/jet/modules/AllModules.java
+++ b/stdlib/src/jet/modules/AllModules.java
@@ -22,5 +22,14 @@ package jet.modules;
 import java.util.ArrayList;
 
 public class AllModules {
-    public static final ArrayList<Module> modules = new ArrayList<Module>();
+
+    public static final ThreadLocal<ArrayList<Module>> modules = new ThreadLocal<ArrayList<Module>>() {
+        @Override
+        protected ArrayList<Module> initialValue() {
+            return new ArrayList<Module>();
+        }
+    };
+
+    private AllModules() {
+    }
 }