diff --git a/platform/lang-impl/src/com/intellij/codeInsight/lookup/impl/CompletionPreview.java b/platform/lang-impl/src/com/intellij/codeInsight/lookup/impl/CompletionPreview.java
index 79669c641453..b3c038591d45 100644
--- a/platform/lang-impl/src/com/intellij/codeInsight/lookup/impl/CompletionPreview.java
+++ b/platform/lang-impl/src/com/intellij/codeInsight/lookup/impl/CompletionPreview.java
@@ -125,7 +125,7 @@ public class CompletionPreview {
         Editor editor = lookup.getEditor();
         CharSequence seq = editor.getDocument().getCharsSequence();
         int caret = editor.getCaretModel().getOffset();
-        if (caret < seq.length() && seq.charAt(caret) != '(') {
+        if (caret >= seq.length() || seq.charAt(caret) != '(') {
           text += "()";
         }
       }