diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java
index 8a2f4d354..e0f0e1355 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsPackFile.java
@@ -310,7 +310,8 @@ private PackObjectSizeIndex getObjectSizeIndex(DfsReader ctx)
 			return objectSizeIndex;
 		}
 
-		if (objectSizeIndexLoadAttempted) {
+		if (objectSizeIndexLoadAttempted
+				|| !desc.hasFileExt(OBJECT_SIZE_INDEX)) {
 			// Pack doesn't have object size index
 			return null;
 		}