diff --git a/src/main/java/org/elasticsearch/search/aggregations/AggregatorFactories.java b/src/main/java/org/elasticsearch/search/aggregations/AggregatorFactories.java
index 87d833a398a..034155be7f8 100644
--- a/src/main/java/org/elasticsearch/search/aggregations/AggregatorFactories.java
+++ b/src/main/java/org/elasticsearch/search/aggregations/AggregatorFactories.java
@@ -19,6 +19,7 @@
 package org.elasticsearch.search.aggregations;
 
 import org.apache.lucene.index.AtomicReaderContext;
+import org.elasticsearch.ElasticsearchIllegalArgumentException;
 import org.elasticsearch.common.lease.Releasables;
 import org.elasticsearch.common.util.ObjectArray;
 import org.elasticsearch.search.aggregations.Aggregator.BucketAggregationMode;
@@ -26,7 +27,9 @@ import org.elasticsearch.search.aggregations.support.AggregationContext;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 /**
  *
@@ -183,9 +186,13 @@ public class AggregatorFactories {
 
     public static class Builder {
 
-        private List<AggregatorFactory> factories = new ArrayList<>();
+        private final Set<String> names = new HashSet<>();
+        private final List<AggregatorFactory> factories = new ArrayList<>();
 
         public Builder add(AggregatorFactory factory) {
+            if (!names.add(factory.name)) {
+                throw new ElasticsearchIllegalArgumentException("Two sibling aggregations cannot have the same name: [" + factory.name + "]");
+            }
             factories.add(factory);
             return this;
         }
diff --git a/src/test/java/org/elasticsearch/search/aggregations/ParsingTests.java b/src/test/java/org/elasticsearch/search/aggregations/ParsingTests.java
index 685bdca3e23..1d3044700a4 100644
--- a/src/test/java/org/elasticsearch/search/aggregations/ParsingTests.java
+++ b/src/test/java/org/elasticsearch/search/aggregations/ParsingTests.java
@@ -19,6 +19,7 @@
 
 package org.elasticsearch.search.aggregations;
 
+import com.carrotsearch.randomizedtesting.generators.RandomStrings;
 import org.elasticsearch.action.search.SearchPhaseExecutionException;
 import org.elasticsearch.common.xcontent.json.JsonXContent;
 import org.elasticsearch.test.ElasticsearchIntegrationTest;
@@ -112,6 +113,26 @@ public class ParsingTests extends ElasticsearchIntegrationTest {
             .endObject()).execute().actionGet();
     }
 
+    @Test(expected=SearchPhaseExecutionException.class)
+    public void testSameAggregationName() throws Exception {
+        createIndex("idx");
+        ensureGreen();
+        final String name = RandomStrings.randomAsciiOfLength(getRandom(), 10);
+        client().prepareSearch("idx").setAggregations(JsonXContent.contentBuilder()
+            .startObject()
+                .startObject(name)
+                    .startObject("terms")
+                        .field("field", "a")
+                    .endObject()
+                .endObject()
+                .startObject(name)
+                    .startObject("terms")
+                        .field("field", "b")
+                    .endObject()
+                .endObject()
+            .endObject()).execute().actionGet();
+    }
+
     @Test(expected=SearchPhaseExecutionException.class)
     public void testMissingName() throws Exception {
         createIndex("idx");