diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index 6ce36f8fdec..ac9974ff584 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -91,6 +91,9 @@ Bug Fixes
   long document in SimilarityBase or BM25Similarity. Add more warnings to sims
   that will not work well with extreme tf values. (Ahmet Arslan, Robert Muir)
 
+* LUCENE-6984: SpanMultiTermQueryWrapper no longer modifies its wrapped query.
+  (Alan Woodward, Adrien Grand)
+
 Other
 
 * LUCENE-6924: Upgrade randomizedtesting to 2.3.2. (Dawid Weiss)
diff --git a/lucene/core/src/java/org/apache/lucene/search/spans/SpanMultiTermQueryWrapper.java b/lucene/core/src/java/org/apache/lucene/search/spans/SpanMultiTermQueryWrapper.java
index e5c18599f8d..a9ce80d8b5b 100644
--- a/lucene/core/src/java/org/apache/lucene/search/spans/SpanMultiTermQueryWrapper.java
+++ b/lucene/core/src/java/org/apache/lucene/search/spans/SpanMultiTermQueryWrapper.java
@@ -20,6 +20,11 @@ package org.apache.lucene.search.spans;
 import java.io.IOException;
 import java.util.Objects;
 
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+
 import org.apache.lucene.index.IndexReader;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.index.TermContext;
@@ -30,11 +35,6 @@ import org.apache.lucene.search.Query;
 import org.apache.lucene.search.ScoringRewrite;
 import org.apache.lucene.search.TopTermsRewrite;
 
-import java.io.IOException;
-import java.util.Objects;
-import java.util.List;
-import java.util.ArrayList;
-
 /**
  * Wraps any {@link MultiTermQuery} as a {@link SpanQuery}, 
  * so it can be nested within other SpanQuery classes.
@@ -52,7 +52,9 @@ import java.util.ArrayList;
  * </pre></blockquote>
  */
 public class SpanMultiTermQueryWrapper<Q extends MultiTermQuery> extends SpanQuery {
+
   protected final Q query;
+  private SpanRewriteMethod rewriteMethod;
 
   /**
    * Create a new SpanMultiTermQueryWrapper. 
@@ -67,13 +69,16 @@ public class SpanMultiTermQueryWrapper<Q extends MultiTermQuery> extends SpanQue
   @SuppressWarnings({"rawtypes","unchecked"})
   public SpanMultiTermQueryWrapper(Q query) {
     this.query = Objects.requireNonNull(query);
-    
+    this.rewriteMethod = selectRewriteMethod(query);
+  }
+
+  private static SpanRewriteMethod selectRewriteMethod(MultiTermQuery query) {
     MultiTermQuery.RewriteMethod method = query.getRewriteMethod();
     if (method instanceof TopTermsRewrite) {
       final int pqsize = ((TopTermsRewrite) method).getSize();
-      setRewriteMethod(new TopTermsSpanBooleanQueryRewrite(pqsize));
+      return new TopTermsSpanBooleanQueryRewrite(pqsize);
     } else {
-      setRewriteMethod(SCORING_SPAN_QUERY_REWRITE); 
+      return SCORING_SPAN_QUERY_REWRITE;
     }
   }
 
@@ -81,10 +86,7 @@ public class SpanMultiTermQueryWrapper<Q extends MultiTermQuery> extends SpanQue
    * Expert: returns the rewriteMethod
    */
   public final SpanRewriteMethod getRewriteMethod() {
-    final MultiTermQuery.RewriteMethod m = query.getRewriteMethod();
-    if (!(m instanceof SpanRewriteMethod))
-      throw new UnsupportedOperationException("You can only use SpanMultiTermQueryWrapper with a suitable SpanRewriteMethod.");
-    return (SpanRewriteMethod) m;
+    return rewriteMethod;
   }
 
   /**
@@ -92,7 +94,7 @@ public class SpanMultiTermQueryWrapper<Q extends MultiTermQuery> extends SpanQue
    * to be a span rewrite method.
    */
   public final void setRewriteMethod(SpanRewriteMethod rewriteMethod) {
-    query.setRewriteMethod(rewriteMethod);
+    this.rewriteMethod = rewriteMethod;
   }
 
   @Override
@@ -124,10 +126,7 @@ public class SpanMultiTermQueryWrapper<Q extends MultiTermQuery> extends SpanQue
     if (getBoost() != 1f) {
       return super.rewrite(reader);
     }
-    final Query q = query.rewrite(reader);
-    if (!(q instanceof SpanQuery))
-      throw new UnsupportedOperationException("You can only use SpanMultiTermQueryWrapper with a suitable SpanRewriteMethod.");
-    return q;
+    return rewriteMethod.rewrite(reader, query);
   }
   
   @Override
diff --git a/lucene/core/src/test/org/apache/lucene/search/spans/TestSpanMultiTermQueryWrapper.java b/lucene/core/src/test/org/apache/lucene/search/spans/TestSpanMultiTermQueryWrapper.java
index c5023c7f8ff..386f29616f9 100644
--- a/lucene/core/src/test/org/apache/lucene/search/spans/TestSpanMultiTermQueryWrapper.java
+++ b/lucene/core/src/test/org/apache/lucene/search/spans/TestSpanMultiTermQueryWrapper.java
@@ -17,6 +17,8 @@ package org.apache.lucene.search.spans;
  * limitations under the License.
  */
 
+import java.io.IOException;
+
 import org.apache.lucene.document.Document;
 import org.apache.lucene.document.Field;
 import org.apache.lucene.index.IndexReader;
@@ -24,11 +26,13 @@ import org.apache.lucene.index.RandomIndexWriter;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.search.FuzzyQuery;
 import org.apache.lucene.search.IndexSearcher;
+import org.apache.lucene.search.MultiTermQuery;
 import org.apache.lucene.search.PrefixQuery;
 import org.apache.lucene.search.RegexpQuery;
 import org.apache.lucene.search.WildcardQuery;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.util.LuceneTestCase;
+import org.junit.Test;
 
 /**
  * Tests for {@link SpanMultiTermQueryWrapper}, wrapping a few MultiTermQueries.
@@ -226,4 +230,19 @@ public class TestSpanMultiTermQueryWrapper extends LuceneTestCase {
     spanFirst = new SpanFirstQuery(spanPrfxNoSuch, 10);
     assertEquals(0, searcher.search(spanFirst, 10).totalHits);
   }
+
+  @Test
+  public void testWrappedQueryIsNotModified() {
+    final PrefixQuery pq = new PrefixQuery(new Term("field", "test"));
+    int pqHash = pq.hashCode();
+    SpanMultiTermQueryWrapper<PrefixQuery> wrapper = new SpanMultiTermQueryWrapper<>(pq);
+    assertEquals(pqHash, pq.hashCode());
+    wrapper.setRewriteMethod(new SpanMultiTermQueryWrapper.SpanRewriteMethod() {
+      @Override
+      public SpanQuery rewrite(IndexReader reader, MultiTermQuery query) throws IOException {
+        return null;
+      }
+    });
+    assertEquals(pqHash, pq.hashCode());
+  }
 }