diff --git a/java/com/google/gerrit/testing/InMemoryModule.java b/java/com/google/gerrit/testing/InMemoryModule.java
index 06d9453..12da2c1 100644
--- a/java/com/google/gerrit/testing/InMemoryModule.java
+++ b/java/com/google/gerrit/testing/InMemoryModule.java
@@ -134,7 +134,6 @@
     cfg.setString("user", null, "name", "Gerrit Code Review");
     cfg.setString("user", null, "email", "gerrit@localhost");
     cfg.unset("cache", null, "directory");
-    cfg.setString("index", null, "type", "lucene");
     cfg.setBoolean("index", "lucene", "testInmemory", true);
     cfg.setInt("sendemail", null, "threadPoolSize", 0);
     cfg.setBoolean("receive", null, "enableSignedPush", false);
@@ -240,7 +239,8 @@
     bind(AllChangesIndexer.class).toProvider(Providers.of(null));
     bind(AllGroupsIndexer.class).toProvider(Providers.of(null));
 
-    IndexType indexType = new IndexType(cfg.getString("index", null, "type"));
+    String indexTypeCfg = cfg.getString("index", null, "type");
+    IndexType indexType = new IndexType(indexTypeCfg != null ? indexTypeCfg : "fake");
     // For custom index types, callers must provide their own module.
     if (indexType.isLucene()) {
       install(luceneIndexModule());
diff --git a/java/com/google/gerrit/testing/IndexConfig.java b/java/com/google/gerrit/testing/IndexConfig.java
index daef2b3..d68dcad 100644
--- a/java/com/google/gerrit/testing/IndexConfig.java
+++ b/java/com/google/gerrit/testing/IndexConfig.java
@@ -38,7 +38,9 @@
   }
 
   public static Config createForLucene() {
-    return create();
+    Config cfg = create();
+    cfg.setString("index", null, "type", "lucene");
+    return cfg;
   }
 
   public static Config createForElasticsearch() {