diff --git a/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/MultisiteReplicationPushFilter.java b/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/MultisiteReplicationPushFilter.java
index 94a0a9b..5f25607 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/MultisiteReplicationPushFilter.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/multisite/validation/MultisiteReplicationPushFilter.java
@@ -84,7 +84,7 @@
   }
 
   private String changePrefix(String changeRef) {
-    if (!changeRef.startsWith("refs/changes")) {
+    if (changeRef == null || !changeRef.startsWith("refs/changes")) {
       return changeRef;
     }
     if (changeRef.endsWith(REF_META_SUFFIX)) {