diff --git a/repository/index.go b/repository/index.go
index 979401a91..b89d8f25e 100644
--- a/repository/index.go
+++ b/repository/index.go
@@ -64,8 +64,8 @@ const (
 	indexMaxAge   = 15 * time.Minute
 )
 
-// Full returns true iff the index is "full enough" to be saved as a preliminary index.
-func (idx *Index) Full() bool {
+// IndexFull returns true iff the index is "full enough" to be saved as a preliminary index.
+var IndexFull = func(idx *Index) bool {
 	idx.m.Lock()
 	defer idx.m.Unlock()
 
diff --git a/repository/master_index.go b/repository/master_index.go
index c6efc20e4..4d52789af 100644
--- a/repository/master_index.go
+++ b/repository/master_index.go
@@ -206,7 +206,7 @@ func (mi *MasterIndex) FullIndexes() []*Index {
 			continue
 		}
 
-		if idx.Full() {
+		if IndexFull(idx) {
 			debug.Log("MasterIndex.FullIndexes", "index %p is full", idx)
 			list = append(list, idx)
 		} else {