diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/git/SubmoduleOp.java b/gerrit-server/src/main/java/com/google/gerrit/server/git/SubmoduleOp.java
index 20252253e9..a3e9e9f175 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/git/SubmoduleOp.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/git/SubmoduleOp.java
@@ -268,6 +268,9 @@ public class SubmoduleOp {
 
       for (final Map.Entry<Branch.NameKey, ObjectId> me : modules.entrySet()) {
         RevCommit c = myRw.parseCommit(me.getValue());
+        if (c == null) {
+          continue;
+        }
 
         msgbuf.append("\nProject: ");
         msgbuf.append(me.getKey().getParentKey().get());