diff --git a/lib/indexes.js b/lib/indexes.js
index cb000b3..13e1a3c 100644
--- a/lib/indexes.js
+++ b/lib/indexes.js
@@ -62,7 +62,9 @@ Index.prototype.reset = function (newData) {
  * O(log(n))
  */
 Index.prototype.insert = function (doc) {
-  var key, self = this;
+  var key, self = this
+    , keys, i, failingI, error
+    ;
 
   if (util.isArray(doc)) { this.insertMultipleDocs(doc); return; }
 
@@ -74,9 +76,26 @@ Index.prototype.insert = function (doc) {
   if (!util.isArray(key)) {
     this.tree.insert(key, doc);
   } else {
-    _.uniq(key, projectForUnique).forEach(function (_key) {
-      self.tree.insert(_key, doc);
-    });
+    // If an insert fails due to a unique constraint, roll back all inserts before it
+    keys = _.uniq(key, projectForUnique);
+
+    for (i = 0; i < keys.length; i += 1) {
+      try {
+        this.tree.insert(keys[i], doc);
+      } catch (e) {
+        error = e;
+        failingI = i;
+        break;
+      }
+    }
+    
+    if (error) {
+      for (i = 0; i < failingI; i += 1) {
+        this.tree.delete(keys[i], doc);
+      }
+      
+      throw error;
+    }
   }
 };
 
diff --git a/test/indexes.test.js b/test/indexes.test.js
index 13399d0..7060c71 100644
--- a/test/indexes.test.js
+++ b/test/indexes.test.js
@@ -177,7 +177,7 @@ describe('Indexes', function () {
       (function () { idx.insert(obj2); }).should.throw();
 	  });
     
-    it('When removing a document, remove it from the index at all array elements', function () {
+    it('When removing a document, remove it from the index at all unique array elements', function () {
       var obj = { tf: ['aa', 'aa'], really: 'yeah' }
         , obj2 = { tf: ['cc', 'aa', 'cc'], yes: 'indeed' }
         , idx = new Index({ fieldName: 'tf' })
@@ -196,6 +196,27 @@ describe('Indexes', function () {
       idx.getMatching('aa').indexOf(obj2).should.equal(-1);
       idx.getMatching('cc').length.should.equal(0);      
     });
+    
+    it('If a unique constraint is violated when inserting an array key, roll back all inserts before the key', function () {
+      var obj = { tf: ['aa', 'bb'], really: 'yeah' }
+        , obj2 = { tf: ['cc', 'dd', 'aa'], yes: 'indeed' }
+        , idx = new Index({ fieldName: 'tf', unique: true })
+        ;
+
+      idx.insert(obj);
+      idx.getAll().length.should.equal(2);
+      idx.getMatching('aa').length.should.equal(1);
+      idx.getMatching('bb').length.should.equal(1);
+      idx.getMatching('cc').length.should.equal(0);
+      idx.getMatching('dd').length.should.equal(0);
+      
+      (function () { idx.insert(obj2); }).should.throw();
+      idx.getAll().length.should.equal(2);
+      idx.getMatching('aa').length.should.equal(1);
+      idx.getMatching('bb').length.should.equal(1);
+      idx.getMatching('cc').length.should.equal(0);
+      idx.getMatching('dd').length.should.equal(0);      
+    });
 	
 	});   // ==== End of 'Array fields' ==== //