diff --git a/src/java/org/apache/lucene/index/SegmentMerger.java b/src/java/org/apache/lucene/index/SegmentMerger.java
index d6c1dbc2e42..f5317c4a272 100644
--- a/src/java/org/apache/lucene/index/SegmentMerger.java
+++ b/src/java/org/apache/lucene/index/SegmentMerger.java
@@ -374,7 +374,7 @@ final class SegmentMerger {
 
       final long fdxFileLength = directory.fileLength(segment + "." + IndexFileNames.FIELDS_INDEX_EXTENSION);
 
-      if (4+docCount*8 != fdxFileLength)
+      if (4+((long) docCount)*8 != fdxFileLength)
         // This is most likely a bug in Sun JRE 1.6.0_04/_05;
         // we detect that the bug has struck, here, and
         // throw an exception to prevent the corruption from
@@ -468,7 +468,7 @@ final class SegmentMerger {
 
     final long tvxSize = directory.fileLength(segment + "." + IndexFileNames.VECTORS_INDEX_EXTENSION);
 
-    if (4+mergedDocs*16 != tvxSize)
+    if (4+((long) mergedDocs)*16 != tvxSize)
       // This is most likely a bug in Sun JRE 1.6.0_04/_05;
       // we detect that the bug has struck, here, and
       // throw an exception to prevent the corruption from