diff --git a/lodash.js b/lodash.js
index d61413c91..5afd69f01 100644
--- a/lodash.js
+++ b/lodash.js
@@ -2380,17 +2380,35 @@
       return high;
     }
 
+    /**
+     * The implementation of `_.uniq` optimized for sorted arrays
+     *
+     * @private
+     * @param {Array} array The array to inspect.
+     * @returns {Array} Returns the new duplicate-value-free array.
+     */
+    function sortedUniq(array) {
+      var result = [],
+          index = -1,
+          length = array ? array.length : 0;
+      while (++index < length) {
+        if (index + 1 > length || array[index] !== array[index + 1]) {
+          result.push(array[index]);
+        }
+      }
+      return result;
+    };
+
     /**
      * The base implementation of `_.uniq` without support for callback shorthands
      * and `this` binding.
      *
      * @private
      * @param {Array} array The array to inspect.
-     * @param {boolean} [isSorted=false] Specify the array is sorted.
      * @param {Function} [iterator] The function called per iteration.
      * @returns {Array} Returns the new duplicate-value-free array.
      */
-    function baseUniq(array, isSorted, iterator) {
+    function baseUniq(array, iterator) {
       var length = array ? array.length : 0;
       if (!length) {
         return [];
@@ -2402,12 +2420,11 @@
           isCommon = prereq && !isLarge,
           result = [];
 
-      isSorted = prereq && isSorted;
       if (isLarge) {
         var seen = createCache();
         indexOf = cacheIndexOf;
       } else {
-        seen = (iterator && !isSorted) ? [] : result;
+        seen = iterator ? [] : result;
       }
       outer:
       while (++index < length) {
@@ -2426,12 +2443,6 @@
           }
           result.push(value);
         }
-        else if (isSorted) {
-          if (!index || seen !== computed) {
-            seen = computed;
-            result.push(value);
-          }
-        }
         else if (indexOf(seen, computed) < 0) {
           if (iterator || isLarge) {
             seen.push(computed);
@@ -4095,26 +4106,23 @@
      * // => [{ 'x': 1 }, { 'x': 2 }]
      */
     function uniq(array, isSorted, iterator, thisArg) {
-      var length = array ? array.length : 0;
-      if (!length) {
-        return [];
-      }
       // juggle arguments
       var type = typeof isSorted;
       if (type != 'boolean' && isSorted != null) {
         thisArg = iterator;
         iterator = isSorted;
-        isSorted = false;
 
         // enables use as a callback for functions like `_.map`
         if ((type == 'number' || type == 'string') && thisArg && thisArg[iterator] === array) {
           iterator = null;
         }
+      } else if (isSorted && getIndexOf() == baseIndexOf) {
+        return sortedUniq(array);
       }
       if (iterator != null) {
         iterator = getCallback(iterator, thisArg, 3);
       }
-      return baseUniq(array, isSorted, iterator);
+      return baseUniq(array, iterator);
     }
 
     /**
diff --git a/test/test.js b/test/test.js
index 7d0cdafc2..ba52874f5 100644
--- a/test/test.js
+++ b/test/test.js
@@ -10683,9 +10683,11 @@
       deepEqual(_.uniq(objects), objects);
     });
 
-    test('should work with `isSorted`', 1, function() {
-      var array = [1, 1, 2, 2, 3];
+    test('should work with `isSorted`', 4, function() {
       deepEqual(_.uniq([1, 1, 2, 2, 3], true), [1, 2, 3]);
+      deepEqual(_.uniq(_.range(100), true), _.range(100));
+      deepEqual(_.uniq(_.times(100, _.constant(undefined))), [undefined]);
+      deepEqual(_.uniq([1, 2, 3, 3, 3, 3, 3]), [1, 2, 3]);
     });
 
     test('should work with a callback', 1, function() {