diff --git a/compiler/cli/src/org/jetbrains/jet/compiler/CompileEnvironment.java b/compiler/cli/src/org/jetbrains/jet/compiler/CompileEnvironment.java
index 72a599d9f26..91737a01a23 100644
--- a/compiler/cli/src/org/jetbrains/jet/compiler/CompileEnvironment.java
+++ b/compiler/cli/src/org/jetbrains/jet/compiler/CompileEnvironment.java
@@ -301,7 +301,8 @@ public class CompileEnvironment {
         String mainClass = null;
         for (JetFile file : session.getSourceFileNamespaces()) {
             if (JetMainDetector.hasMain(file.getDeclarations())) {
-                mainClass = JetPsiUtil.getFQName(file) + "." + JvmAbi.PACKAGE_CLASS;
+                String fqName = JetPsiUtil.getFQName(file);
+                mainClass = fqName.length() > 0 ? fqName + "." + JvmAbi.PACKAGE_CLASS : JvmAbi.PACKAGE_CLASS;
                 break;
             }
         }