diff --git a/src/java/org/apache/lucene/search/BooleanQuery.java b/src/java/org/apache/lucene/search/BooleanQuery.java
index 932db8cd735..6f6673cb760 100644
--- a/src/java/org/apache/lucene/search/BooleanQuery.java
+++ b/src/java/org/apache/lucene/search/BooleanQuery.java
@@ -294,7 +294,9 @@ public class BooleanQuery extends Query {
         BooleanClause c = (BooleanClause) cIter.next();
         Scorer subScorer = w.scorer(reader, true, false);
         if (subScorer == null) {
-          return null;
+          if (c.isRequired()) {
+            return null;
+          }
         } else if (c.isRequired()) {
           required.add(subScorer);
         } else if (c.isProhibited()) {
diff --git a/src/java/org/apache/lucene/search/DisjunctionMaxQuery.java b/src/java/org/apache/lucene/search/DisjunctionMaxQuery.java
index a2edd224861..3a0969e3652 100644
--- a/src/java/org/apache/lucene/search/DisjunctionMaxQuery.java
+++ b/src/java/org/apache/lucene/search/DisjunctionMaxQuery.java
@@ -134,9 +134,7 @@ public class DisjunctionMaxQuery extends Query {
       for (Iterator iter = weights.iterator(); iter.hasNext();) {
         QueryWeight w = (QueryWeight) iter.next();
         Scorer subScorer = w.scorer(reader, true, false);
-        if (subScorer == null) {
-          return null;
-        } else if (subScorer.nextDoc() != DocIdSetIterator.NO_MORE_DOCS) {
+        if (subScorer != null && subScorer.nextDoc() != DocIdSetIterator.NO_MORE_DOCS) {
           scorers[idx++] = subScorer;
         }
       }
diff --git a/src/java/org/apache/lucene/search/IndexSearcher.java b/src/java/org/apache/lucene/search/IndexSearcher.java
index ace8989d7d7..203f524fb24 100644
--- a/src/java/org/apache/lucene/search/IndexSearcher.java
+++ b/src/java/org/apache/lucene/search/IndexSearcher.java
@@ -219,7 +219,9 @@ public class IndexSearcher extends Searcher {
       hcw.setNextReader(reader, 0);
       if (filter == null) {
         Scorer scorer = weight.scorer(reader, true, true);
-        scorer.score(hcw);
+        if (scorer != null) {
+          scorer.score(hcw);
+        }
       } else {
         searchWithFilter(reader, weight, filter, hcw);
       }
@@ -239,7 +241,9 @@ public class IndexSearcher extends Searcher {
       for (int i = 0; i < subReaders.length; i++) { // search each subreader
         collector.setNextReader(subReaders[i], docStarts[i]);
         Scorer scorer = weight.scorer(subReaders[i], !collector.acceptsDocsOutOfOrder(), true);
-        scorer.score(collector);
+        if (scorer != null) {
+          scorer.score(collector);
+        }
       }
     } else {
       for (int i = 0; i < subReaders.length; i++) { // search each subreader
diff --git a/src/test/org/apache/lucene/search/TestBooleanQuery.java b/src/test/org/apache/lucene/search/TestBooleanQuery.java
index 13b06210ac6..e452a75af1f 100644
--- a/src/test/org/apache/lucene/search/TestBooleanQuery.java
+++ b/src/test/org/apache/lucene/search/TestBooleanQuery.java
@@ -16,7 +16,13 @@ package org.apache.lucene.search;
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
+import org.apache.lucene.index.IndexWriter;
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.analysis.WhitespaceAnalyzer;
+import org.apache.lucene.store.MockRAMDirectory;
+import org.apache.lucene.store.Directory;
 import org.apache.lucene.util.LuceneTestCase;
 import org.apache.lucene.index.Term;
 
@@ -50,5 +56,32 @@ public class TestBooleanQuery extends LuceneTestCase {
       // okay
     }
   }
+
+  // LUCENE-1630
+  public void testNullOrSubScorer() throws Throwable {
+    Directory dir = new MockRAMDirectory();
+    IndexWriter w = new IndexWriter(dir, new WhitespaceAnalyzer(), IndexWriter.MaxFieldLength.UNLIMITED);
+    Document doc = new Document();
+    doc.add(new Field("field", "a b c d", Field.Store.NO, Field.Index.ANALYZED));
+    w.addDocument(doc);
+    IndexReader r = w.getReader();
+    IndexSearcher s = new IndexSearcher(r);
+    BooleanQuery q = new BooleanQuery();
+    q.add(new TermQuery(new Term("field", "a")), BooleanClause.Occur.SHOULD);
+
+    // PhraseQuery w/ no terms added returns a null scorer
+    PhraseQuery pq = new PhraseQuery();
+    q.add(pq, BooleanClause.Occur.SHOULD);
+    assertEquals(1, s.search(q, 10).totalHits);
+
+    DisjunctionMaxQuery dmq = new DisjunctionMaxQuery(1.0f);
+    dmq.add(new TermQuery(new Term("field", "a")));
+    dmq.add(pq);
+    assertEquals(1, s.search(dmq, 10).totalHits);
+    
+    r.close();
+    w.close();
+    dir.close();
+  }
   
 }