diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index f4fa8ba5c9b..e7e3e28bb3a 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -126,6 +126,8 @@ Bug Fixes
   other ranges had more than one clause matching (Ahmet Arslan,
   hossman, Mike McCandless)
 
+* LUCENE-7286: Added support for highlighting SynonymQuery. (Adrien Grand)
+
 Other
 
 * LUCENE-7295: TermAutomatonQuery.hashCode calculates Automaton.toDot().hash,
diff --git a/lucene/highlighter/src/java/org/apache/lucene/search/highlight/WeightedSpanTermExtractor.java b/lucene/highlighter/src/java/org/apache/lucene/search/highlight/WeightedSpanTermExtractor.java
index 43f75ccb335..7507bdde6e8 100644
--- a/lucene/highlighter/src/java/org/apache/lucene/search/highlight/WeightedSpanTermExtractor.java
+++ b/lucene/highlighter/src/java/org/apache/lucene/search/highlight/WeightedSpanTermExtractor.java
@@ -53,6 +53,7 @@ import org.apache.lucene.search.MultiPhraseQuery;
 import org.apache.lucene.search.MultiTermQuery;
 import org.apache.lucene.search.PhraseQuery;
 import org.apache.lucene.search.Query;
+import org.apache.lucene.search.SynonymQuery;
 import org.apache.lucene.search.TermQuery;
 import org.apache.lucene.search.join.ToChildBlockJoinQuery;
 import org.apache.lucene.search.join.ToParentBlockJoinQuery;
@@ -138,7 +139,7 @@ public class WeightedSpanTermExtractor {
         SpanNearQuery sp = new SpanNearQuery(clauses, phraseQuery.getSlop() + positionGaps, inorder);
         extractWeightedSpanTerms(terms, sp, boost);
       }
-    } else if (query instanceof TermQuery) {
+    } else if (query instanceof TermQuery || query instanceof SynonymQuery) {
       extractWeightedTerms(terms, query, boost);
     } else if (query instanceof SpanQuery) {
       extractWeightedSpanTerms(terms, (SpanQuery) query, boost);
diff --git a/lucene/highlighter/src/test/org/apache/lucene/search/highlight/HighlighterTest.java b/lucene/highlighter/src/test/org/apache/lucene/search/highlight/HighlighterTest.java
index 3c6f1086d7e..cf727d7154a 100644
--- a/lucene/highlighter/src/test/org/apache/lucene/search/highlight/HighlighterTest.java
+++ b/lucene/highlighter/src/test/org/apache/lucene/search/highlight/HighlighterTest.java
@@ -71,6 +71,7 @@ import org.apache.lucene.search.PhraseQuery.Builder;
 import org.apache.lucene.search.PrefixQuery;
 import org.apache.lucene.search.Query;
 import org.apache.lucene.search.RegexpQuery;
+import org.apache.lucene.search.SynonymQuery;
 import org.apache.lucene.search.TermQuery;
 import org.apache.lucene.search.TermRangeQuery;
 import org.apache.lucene.search.TopDocs;
@@ -223,6 +224,24 @@ public class HighlighterTest extends BaseTokenStreamTestCase implements Formatte
     assertEquals("This piece of text refers to Kennedy at the beginning then has a longer piece of text that is <B>very</B>", fragment);
   }
 
+  public void testHighlightingSynonymQuery() throws Exception {
+    searcher = newSearcher(reader);
+    Query query = new SynonymQuery(new Term(FIELD_NAME, "jfk"), new Term(FIELD_NAME, "kennedy"));
+    QueryScorer scorer = new QueryScorer(query, FIELD_NAME);
+    Highlighter highlighter = new Highlighter(scorer);
+    TokenStream stream = getAnyTokenStream(FIELD_NAME, 2);
+    Fragmenter fragmenter = new SimpleSpanFragmenter(scorer);
+    highlighter.setTextFragmenter(fragmenter);
+    String storedField = searcher.doc(2).get(FIELD_NAME);
+    String fragment = highlighter.getBestFragment(stream, storedField);
+    assertEquals("<B>JFK</B> has been shot", fragment);
+
+    stream = getAnyTokenStream(FIELD_NAME, 3);
+    storedField = searcher.doc(3).get(FIELD_NAME);
+    fragment = highlighter.getBestFragment(stream, storedField);
+    assertEquals("John <B>Kennedy</B> has been shot", fragment);
+  }
+
   public void testHighlightUnknownQueryAfterRewrite() throws IOException, InvalidTokenOffsetsException {
     Query query = new Query() {
       
@@ -2093,7 +2112,7 @@ public class HighlighterTest extends BaseTokenStreamTestCase implements Formatte
     analyzer = new MockAnalyzer(random(), MockTokenizer.SIMPLE, true, MockTokenFilter.ENGLISH_STOPSET);
     ramDir = newDirectory();
     fieldType = random().nextBoolean() ? FIELD_TYPE_TV : TextField.TYPE_STORED;
-    IndexWriter writer = new IndexWriter(ramDir, newIndexWriterConfig(analyzer));
+    IndexWriter writer = new IndexWriter(ramDir, newIndexWriterConfig(analyzer).setMergePolicy(newLogMergePolicy()));
 
     for (String text : texts) {
       writer.addDocument(doc(FIELD_NAME, text));