diff --git a/java/openapi/src/com/intellij/codeInsight/generation/surroundWith/JavaExpressionSurrounder.java b/java/openapi/src/com/intellij/codeInsight/generation/surroundWith/JavaExpressionSurrounder.java
index 1265068bcbd1..d0fbb4753667 100644
--- a/java/openapi/src/com/intellij/codeInsight/generation/surroundWith/JavaExpressionSurrounder.java
+++ b/java/openapi/src/com/intellij/codeInsight/generation/surroundWith/JavaExpressionSurrounder.java
@@ -1,6 +1,5 @@
-
 /*
- * Copyright 2000-2009 JetBrains s.r.o.
+ * Copyright 2000-2015 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -14,11 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package com.intellij.codeInsight.generation.surroundWith;
 
 import com.intellij.lang.surroundWith.Surrounder;
-import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.editor.Editor;
 import com.intellij.openapi.extensions.ExtensionPointName;
 import com.intellij.openapi.project.Project;
@@ -28,15 +25,16 @@ import com.intellij.psi.PsiExpression;
 import com.intellij.util.IncorrectOperationException;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.Arrays;
+
 public abstract class JavaExpressionSurrounder implements Surrounder {
   public static ExtensionPointName<JavaExpressionSurrounder> EP_NAME = ExtensionPointName.create("com.intellij.javaExpressionSurrounder");
-  
-  private static final Logger LOG = Logger.getInstance("#com.intellij.codeInsight.generation.surroundWith.SurroundExpressionHandler");
 
   @Override
   public boolean isApplicable(@NotNull PsiElement[] elements) {
-    LOG.assertTrue(elements.length == 1 && elements[0] instanceof PsiExpression);
-    return isApplicable((PsiExpression)elements[0]);
+    return elements.length == 1 &&
+           elements[0] instanceof PsiExpression &&
+           isApplicable((PsiExpression)elements[0]);
   }
 
   public abstract boolean isApplicable(PsiExpression expr);
@@ -45,8 +43,11 @@ public abstract class JavaExpressionSurrounder implements Surrounder {
   public TextRange surroundElements(@NotNull Project project,
                                     @NotNull Editor editor,
                                     @NotNull PsiElement[] elements) throws IncorrectOperationException {
+    if (elements.length != 1 || !(elements[0] instanceof PsiExpression)) {
+      throw new IllegalArgumentException(Arrays.toString(elements));
+    }
     return surroundExpression(project, editor, (PsiExpression)elements[0]);
   }
 
   public abstract TextRange surroundExpression(Project project, Editor editor, PsiExpression expr) throws IncorrectOperationException;
-}
\ No newline at end of file
+}