diff --git a/services/src/main/java/io/grpc/protobuf/services/ChannelzProtoUtil.java b/services/src/main/java/io/grpc/protobuf/services/ChannelzProtoUtil.java
index 987884c4a6a..58183ad017d 100644
--- a/services/src/main/java/io/grpc/protobuf/services/ChannelzProtoUtil.java
+++ b/services/src/main/java/io/grpc/protobuf/services/ChannelzProtoUtil.java
@@ -394,7 +394,10 @@ private static List<ChannelTraceEvent> toChannelTraceEvents(List<Event> events)
     return Collections.unmodifiableList(channelTraceEvents);
   }
 
-  private static Severity toSeverity(Event.Severity severity) {
+  static Severity toSeverity(Event.Severity severity) {
+    if (severity == null) {
+      return Severity.CT_UNKNOWN;
+    }
     switch (severity) {
       case CT_INFO:
         return Severity.CT_INFO;
diff --git a/services/src/test/java/io/grpc/protobuf/services/ChannelzProtoUtilTest.java b/services/src/test/java/io/grpc/protobuf/services/ChannelzProtoUtilTest.java
index 1b2219a42af..598a8625e58 100644
--- a/services/src/test/java/io/grpc/protobuf/services/ChannelzProtoUtilTest.java
+++ b/services/src/test/java/io/grpc/protobuf/services/ChannelzProtoUtilTest.java
@@ -350,6 +350,16 @@ public void toServerRef() {
     assertEquals(serverRef, ChannelzProtoUtil.toServerRef(server));
   }
 
+  @Test
+  public void toSeverity() {
+    for (Severity severity : Severity.values()) {
+      assertEquals(
+          severity.name(),
+          ChannelzProtoUtil.toSeverity(severity).name()); // OK because test isn't proguarded.
+    }
+    assertEquals(ChannelTraceEvent.Severity.CT_UNKNOWN, ChannelzProtoUtil.toSeverity(null));
+  }
+
   @Test
   public void toSocketRef() {
     assertEquals(socketRef, ChannelzProtoUtil.toSocketRef(socket));