diff --git a/platform/core-api/src/com/intellij/openapi/vfs/VirtualFileWithoutContent.java b/platform/core-api/src/com/intellij/openapi/vfs/VirtualFileWithoutContent.java
new file mode 100644
index 000000000000..2651966568e4
--- /dev/null
+++ b/platform/core-api/src/com/intellij/openapi/vfs/VirtualFileWithoutContent.java
@@ -0,0 +1,22 @@
+/*
+ * Copyright 2000-2016 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.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.openapi.vfs;
+
+/**
+ * @author Irina.Chernushina on 7/4/2016.
+ */
+public interface VirtualFileWithoutContent {
+}
diff --git a/platform/diff-impl/src/com/intellij/diff/actions/BaseShowDiffAction.java b/platform/diff-impl/src/com/intellij/diff/actions/BaseShowDiffAction.java
index 4f3a3627bf78..e918a207063e 100644
--- a/platform/diff-impl/src/com/intellij/diff/actions/BaseShowDiffAction.java
+++ b/platform/diff-impl/src/com/intellij/diff/actions/BaseShowDiffAction.java
@@ -23,6 +23,8 @@ import com.intellij.openapi.actionSystem.AnActionEvent;
 import com.intellij.openapi.actionSystem.Presentation;
 import com.intellij.openapi.project.DumbAware;
 import com.intellij.openapi.project.Project;
+import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.openapi.vfs.VirtualFileWithoutContent;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -48,6 +50,10 @@ abstract class BaseShowDiffAction extends AnAction implements DumbAware {
 
   protected abstract boolean isAvailable(@NotNull AnActionEvent e);
 
+  protected static boolean hasContent(VirtualFile file) {
+    return ! (file instanceof VirtualFileWithoutContent);
+  }
+
   @Nullable
   protected abstract DiffRequest getDiffRequest(@NotNull AnActionEvent e);
 }
diff --git a/platform/diff-impl/src/com/intellij/diff/actions/CompareFileWithEditorAction.java b/platform/diff-impl/src/com/intellij/diff/actions/CompareFileWithEditorAction.java
index bbaa285236a1..7f27f7ff45b4 100644
--- a/platform/diff-impl/src/com/intellij/diff/actions/CompareFileWithEditorAction.java
+++ b/platform/diff-impl/src/com/intellij/diff/actions/CompareFileWithEditorAction.java
@@ -72,7 +72,7 @@ public class CompareFileWithEditorAction extends BaseShowDiffAction {
   }
 
   private static boolean canCompare(@NotNull VirtualFile file1, @NotNull VirtualFile file2) {
-    return file1.isValid() && file2.isValid() && !file1.equals(file2);
+    return file1.isValid() && file2.isValid() && !file1.equals(file2) && hasContent(file1) && hasContent(file2);
   }
 
   @Nullable
diff --git a/platform/diff-impl/src/com/intellij/diff/actions/CompareFilesAction.java b/platform/diff-impl/src/com/intellij/diff/actions/CompareFilesAction.java
index 39f47ddda532..6ac2e1f4a63c 100644
--- a/platform/diff-impl/src/com/intellij/diff/actions/CompareFilesAction.java
+++ b/platform/diff-impl/src/com/intellij/diff/actions/CompareFilesAction.java
@@ -83,20 +83,16 @@ public class CompareFilesAction extends BaseShowDiffAction {
     }
 
     if (files.length == 1) {
-      return isValidAndLocal(files[0]);
+      return hasContent(files[0]);
     }
     else if (files.length == 2) {
-      return isValidAndLocal(files[0]) && isValidAndLocal(files[1]);
+      return hasContent(files[0]) && hasContent(files[1]);
     }
     else {
       return false;
     }
   }
 
-  private static boolean isValidAndLocal(VirtualFile file) {
-    return file.isValid() && file.isInLocalFileSystem();
-  }
-
   @Nullable
   @Override
   protected DiffRequest getDiffRequest(@NotNull AnActionEvent e) {
diff --git a/plugins/properties/src/com/intellij/lang/properties/editor/ResourceBundleAsVirtualFile.java b/plugins/properties/src/com/intellij/lang/properties/editor/ResourceBundleAsVirtualFile.java
index bfc20426a5d0..26f83ecd2f76 100644
--- a/plugins/properties/src/com/intellij/lang/properties/editor/ResourceBundleAsVirtualFile.java
+++ b/plugins/properties/src/com/intellij/lang/properties/editor/ResourceBundleAsVirtualFile.java
@@ -22,8 +22,8 @@ import com.intellij.lang.properties.psi.PropertiesFile;
 import com.intellij.openapi.vfs.LocalFileSystem;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.openapi.vfs.VirtualFileSystem;
+import com.intellij.openapi.vfs.VirtualFileWithoutContent;
 import com.intellij.openapi.vfs.newvfs.RefreshQueue;
-import com.intellij.util.Function;
 import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
 
@@ -36,7 +36,7 @@ import java.util.List;
  * @author Alexey
  */
 @Presentation(icon = "AllIcons.Nodes.ResourceBundle")
-public class ResourceBundleAsVirtualFile extends VirtualFile {
+public class ResourceBundleAsVirtualFile extends VirtualFile implements VirtualFileWithoutContent {
   private final ResourceBundle myResourceBundle;
 
   public ResourceBundleAsVirtualFile(@NotNull final ResourceBundle resourceBundle) {