diff --git a/src/main/java/org/elasticsearch/common/rounding/TimeZoneRounding.java b/src/main/java/org/elasticsearch/common/rounding/TimeZoneRounding.java
index d795013577255..1e04b5d4c4a6a 100644
--- a/src/main/java/org/elasticsearch/common/rounding/TimeZoneRounding.java
+++ b/src/main/java/org/elasticsearch/common/rounding/TimeZoneRounding.java
@@ -162,7 +162,7 @@ public long valueForKey(long time) {
 
         @Override
         public long nextRoundingValue(long value) {
-            return unit.field().roundCeiling(value + 1);
+            return unit.field().getDurationField().add(value, 1);
         }
 
         @Override
@@ -210,7 +210,7 @@ public long valueForKey(long key) {
 
         @Override
         public long nextRoundingValue(long value) {
-            return unit.field().roundCeiling(value + 1);
+            return unit.field().getDurationField().add(value, 1);
         }
 
         @Override
@@ -262,7 +262,7 @@ public long valueForKey(long time) {
 
         @Override
         public long nextRoundingValue(long value) {
-            return unit.field().getDurationField().getUnitMillis() + value;
+            return unit.field().getDurationField().add(value, 1);
         }
 
         @Override
diff --git a/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalHistogram.java b/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalHistogram.java
index 94286b32156f9..ef39438406318 100644
--- a/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalHistogram.java
+++ b/src/main/java/org/elasticsearch/search/aggregations/bucket/histogram/InternalHistogram.java
@@ -320,10 +320,11 @@ public InternalAggregation reduce(ReduceContext reduceContext) {
                 B nextBucket = list.get(iter.nextIndex());
                 if (lastBucket != null) {
                     long key = emptyBucketInfo.rounding.nextRoundingValue(lastBucket.key);
-                    while (key != nextBucket.key) {
+                    while (key < nextBucket.key) {
                         iter.add(createBucket(key, 0, emptyBucketInfo.subAggregations, formatter));
                         key = emptyBucketInfo.rounding.nextRoundingValue(key);
                     }
+                    assert key == nextBucket.key;
                 }
                 lastBucket = iter.next();
             }
diff --git a/src/test/java/org/elasticsearch/search/aggregations/bucket/DateHistogramTests.java b/src/test/java/org/elasticsearch/search/aggregations/bucket/DateHistogramTests.java
index 2e392dfe4d017..021632fc92e99 100644
--- a/src/test/java/org/elasticsearch/search/aggregations/bucket/DateHistogramTests.java
+++ b/src/test/java/org/elasticsearch/search/aggregations/bucket/DateHistogramTests.java
@@ -1299,4 +1299,36 @@ public void singleValue_WithMultipleDateFormatsFromMapping() throws Exception {
         assertThat(bucket, Matchers.notNullValue());
         assertThat(bucket.getDocCount(), equalTo(5l));
     }
+
+    public void testIssue6965() {
+        SearchResponse response = client().prepareSearch("idx")
+                .addAggregation(dateHistogram("histo").field("date").preZone("+01:00").interval(DateHistogram.Interval.MONTH).minDocCount(0))
+                .execute().actionGet();
+
+        assertSearchResponse(response);
+
+
+        DateHistogram histo = response.getAggregations().get("histo");
+        assertThat(histo, notNullValue());
+        assertThat(histo.getName(), equalTo("histo"));
+        assertThat(histo.getBuckets().size(), equalTo(3));
+
+        DateTime key = new DateTime(2012, 1, 1, 0, 0, DateTimeZone.UTC);
+        DateHistogram.Bucket bucket = getBucket(histo, key);
+        assertThat(bucket, notNullValue());
+        assertThat(bucket.getKeyAsNumber().longValue(), equalTo(key.getMillis()));
+        assertThat(bucket.getDocCount(), equalTo(1l));
+
+        key = new DateTime(2012, 2, 1, 0, 0, DateTimeZone.UTC);
+        bucket = getBucket(histo, key);
+        assertThat(bucket, notNullValue());
+        assertThat(bucket.getKeyAsNumber().longValue(), equalTo(key.getMillis()));
+        assertThat(bucket.getDocCount(), equalTo(2l));
+
+        key = new DateTime(2012, 3, 1, 0, 0, DateTimeZone.UTC);
+        bucket = getBucket(histo, key);
+        assertThat(bucket, notNullValue());
+        assertThat(bucket.getKeyAsNumber().longValue(), equalTo(key.getMillis()));
+        assertThat(bucket.getDocCount(), equalTo(3l));
+    }
 }