diff --git a/core/java/android/os/FileUtils.java b/core/java/android/os/FileUtils.java
index 0d9b91b..44ae6ee 100644
--- a/core/java/android/os/FileUtils.java
+++ b/core/java/android/os/FileUtils.java
@@ -605,6 +605,22 @@
         return null;
     }
 
+    private static File buildUniqueFileWithExtension(File parent, String name, String ext)
+            throws FileNotFoundException {
+        File file = buildFile(parent, name, ext);
+
+        // If conflicting file, try adding counter suffix
+        int n = 0;
+        while (file.exists()) {
+            if (n++ >= 32) {
+                throw new FileNotFoundException("Failed to create unique file");
+            }
+            file = buildFile(parent, name + " (" + n + ")", ext);
+        }
+
+        return file;
+    }
+
     /**
      * Generates a unique file name under the given parent directory. If the display name doesn't
      * have an extension that matches the requested MIME type, the default extension for that MIME
@@ -619,20 +635,29 @@
     public static File buildUniqueFile(File parent, String mimeType, String displayName)
             throws FileNotFoundException {
         final String[] parts = splitFileName(mimeType, displayName);
-        final String name = parts[0];
-        final String ext = parts[1];
-        File file = buildFile(parent, name, ext);
+        return buildUniqueFileWithExtension(parent, parts[0], parts[1]);
+    }
 
-        // If conflicting file, try adding counter suffix
-        int n = 0;
-        while (file.exists()) {
-            if (n++ >= 32) {
-                throw new FileNotFoundException("Failed to create unique file");
-            }
-            file = buildFile(parent, name + " (" + n + ")", ext);
+    /**
+     * Generates a unique file name under the given parent directory, keeping
+     * any extension intact.
+     */
+    public static File buildUniqueFile(File parent, String displayName)
+            throws FileNotFoundException {
+        final String name;
+        final String ext;
+
+        // Extract requested extension from display name
+        final int lastDot = displayName.lastIndexOf('.');
+        if (lastDot >= 0) {
+            name = displayName.substring(0, lastDot);
+            ext = displayName.substring(lastDot + 1);
+        } else {
+            name = displayName;
+            ext = null;
         }
 
-        return file;
+        return buildUniqueFileWithExtension(parent, name, ext);
     }
 
     /**
diff --git a/core/tests/coretests/src/android/os/FileUtilsTest.java b/core/tests/coretests/src/android/os/FileUtilsTest.java
index ac5abad..bd90079 100644
--- a/core/tests/coretests/src/android/os/FileUtilsTest.java
+++ b/core/tests/coretests/src/android/os/FileUtilsTest.java
@@ -297,6 +297,20 @@
                 FileUtils.buildUniqueFile(mTarget, "image/jpeg", "test.jpg"));
     }
 
+    public void testBuildUniqueFile_mimeless() throws Exception {
+        assertNameEquals("test.jpg", FileUtils.buildUniqueFile(mTarget, "test.jpg"));
+        new File(mTarget, "test.jpg").createNewFile();
+        assertNameEquals("test (1).jpg", FileUtils.buildUniqueFile(mTarget, "test.jpg"));
+
+        assertNameEquals("test", FileUtils.buildUniqueFile(mTarget, "test"));
+        new File(mTarget, "test").createNewFile();
+        assertNameEquals("test (1)", FileUtils.buildUniqueFile(mTarget, "test"));
+
+        assertNameEquals("test.foo.bar", FileUtils.buildUniqueFile(mTarget, "test.foo.bar"));
+        new File(mTarget, "test.foo.bar").createNewFile();
+        assertNameEquals("test.foo (1).bar", FileUtils.buildUniqueFile(mTarget, "test.foo.bar"));
+    }
+
     private static void assertNameEquals(String expected, File actual) {
         assertEquals(expected, actual.getName());
     }
diff --git a/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java b/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java
index 2812a63..1fe88f0 100644
--- a/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java
+++ b/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java
@@ -473,10 +473,7 @@
         displayName = FileUtils.buildValidFatFilename(displayName);
 
         final File before = getFileForDocId(docId);
-        final File after = new File(before.getParentFile(), displayName);
-        if (after.exists()) {
-            throw new IllegalStateException("Already exists " + after);
-        }
+        final File after = FileUtils.buildUniqueFile(before.getParentFile(), displayName);
         if (!before.renameTo(after)) {
             throw new IllegalStateException("Failed to rename to " + after);
         }