diff --git a/cmd/godoc/main.go b/cmd/godoc/main.go
index 6c21e66b..46938734 100644
--- a/cmd/godoc/main.go
+++ b/cmd/godoc/main.go
@@ -221,6 +221,7 @@ func main() {
 	corpus.IndexThrottle = *indexThrottle
 	if *writeIndex {
 		corpus.IndexThrottle = 1.0
+		corpus.IndexEnabled = true
 	}
 	if *writeIndex || httpMode || *urlFlag != "" {
 		if err := corpus.Init(); err != nil {
diff --git a/godoc/index.go b/godoc/index.go
index eb5182de..efccd64c 100644
--- a/godoc/index.go
+++ b/godoc/index.go
@@ -1477,10 +1477,11 @@ func (c *Corpus) UpdateIndex() {
 func (c *Corpus) RunIndexer() {
 	// initialize the index from disk if possible
 	if c.IndexFiles != "" {
+		c.initFSTree()
 		if err := c.readIndex(c.IndexFiles); err != nil {
 			log.Printf("error reading index from file %s: %v", c.IndexFiles, err)
-			return
 		}
+		return
 	}
 
 	// Repeatedly update the package directory tree and index.