diff --git a/solr/core/src/java/org/apache/solr/update/processor/UpsertCondition.java b/solr/core/src/java/org/apache/solr/update/processor/UpsertCondition.java
index 4af24872ff3..0b8888bd67c 100644
--- a/solr/core/src/java/org/apache/solr/update/processor/UpsertCondition.java
+++ b/solr/core/src/java/org/apache/solr/update/processor/UpsertCondition.java
@@ -399,13 +399,13 @@ private static String getFieldFromDoc(String fieldName, SolrInputDocument doc) {
         return null;
       }
       Object fieldValue = doc.getFieldValue(fieldName);
-      if (fieldValue instanceof String) {
-        return (String)fieldValue;
+      if (fieldValue instanceof CharSequence) {
+        return fieldValue.toString();
       }
       if (fieldValue instanceof Map) {
         final Object setValue = ((Map)fieldValue).get("set");
-        if (setValue instanceof String) {
-          return (String)setValue;
+        if (setValue instanceof CharSequence) {
+          return setValue.toString();
         }
       }
       // Cannot support non-String types or collection (multi-valued field) types
diff --git a/solr/core/src/test/org/apache/solr/update/processor/UpsertConditionTest.java b/solr/core/src/test/org/apache/solr/update/processor/UpsertConditionTest.java
index ad6dee1f1f0..1fd09e0ec90 100644
--- a/solr/core/src/test/org/apache/solr/update/processor/UpsertConditionTest.java
+++ b/solr/core/src/test/org/apache/solr/update/processor/UpsertConditionTest.java
@@ -10,6 +10,7 @@
 import com.google.common.collect.ListMultimap;
 import org.apache.solr.common.SolrException;
 import org.apache.solr.common.SolrInputDocument;
+import org.apache.solr.common.util.ByteArrayUtf8CharSequence;
 import org.apache.solr.common.util.NamedList;
 import org.junit.Test;
 
@@ -872,6 +873,19 @@ public void givenConcatWithOldDoc_whenRunning() {
       assertThat(newDoc.getFieldValue("sku"), is("MacbookSilver"));
     }
 
+    {
+      // Same test but simulating how the javabin format encodes strings
+      SolrInputDocument newDoc = new SolrInputDocument();
+      newDoc.setField("model_name", new ByteArrayUtf8CharSequence("Macbook"));
+      SolrInputDocument oldDoc = new SolrInputDocument();
+      oldDoc.setField("model_name", "Powerbook");
+      oldDoc.setField("colour", "Silver");
+      oldDoc.setField("sku", "PowerbookSilver");
+      assertTrue(condition.matches(oldDoc, newDoc));
+      assertThat(condition.run(oldDoc, newDoc), is(UpsertCondition.ActionType.CONCAT));
+      assertThat(newDoc.getFieldValue("sku"), is("MacbookSilver"));
+    }
+
     {
       SolrInputDocument newDoc = new SolrInputDocument();
       newDoc.setField("model_name", "Macbook");
@@ -966,6 +980,20 @@ public void givenConcatWithAtomicUpdates_whenRunning() {
       assertThat(newDoc.getFieldValue("sku"), is("MacbookSilver"));
     }
 
+    {
+      // Same test but simulating how the javabin format encodes strings
+      SolrInputDocument newDoc = new SolrInputDocument();
+      newDoc.setField("model_name",
+          Collections.singletonMap("set", new ByteArrayUtf8CharSequence("Macbook")));
+      SolrInputDocument oldDoc = new SolrInputDocument();
+      oldDoc.setField("model_name", "Powerbook");
+      oldDoc.setField("colour", "Silver");
+      oldDoc.setField("sku", "PowerbookSilver");
+      assertTrue(condition.matches(oldDoc, newDoc));
+      assertThat(condition.run(oldDoc, newDoc), is(UpsertCondition.ActionType.CONCAT));
+      assertThat(newDoc.getFieldValue("sku"), is("MacbookSilver"));
+    }
+
     {
       SolrInputDocument newDoc = new SolrInputDocument();
       newDoc.setField("unrelated_field", Collections.singletonMap("set", "English"));