diff --git a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/range/InternalRange.java b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/range/InternalRange.java
index 2bc63b377a1..1ae9f1d6aea 100644
--- a/server/src/main/java/org/elasticsearch/search/aggregations/bucket/range/InternalRange.java
+++ b/server/src/main/java/org/elasticsearch/search/aggregations/bucket/range/InternalRange.java
@@ -169,7 +169,7 @@ public class InternalRange<B extends InternalRange.Bucket, R extends InternalRan
 
         @Override
         public void writeTo(StreamOutput out) throws IOException {
-            if (out.getVersion().onOrAfter(Version.V_7_0_0_alpha1)) {
+            if (out.getVersion().onOrAfter(Version.V_6_4_0)) {
                 out.writeString(key);
             } else {
                 out.writeOptionalString(key);
@@ -259,7 +259,7 @@ public class InternalRange<B extends InternalRange.Bucket, R extends InternalRan
         int size = in.readVInt();
         List<B> ranges = new ArrayList<>(size);
         for (int i = 0; i < size; i++) {
-            String key = in.getVersion().onOrAfter(Version.V_7_0_0_alpha1)
+            String key = in.getVersion().onOrAfter(Version.V_6_4_0)
                 ? in.readString()
                 : in.readOptionalString();
             ranges.add(getFactory().createBucket(key, in.readDouble(), in.readDouble(), in.readVLong(),