diff --git a/src/main/java/com/meta/cp4m/message/FBMessageHandler.java b/src/main/java/com/meta/cp4m/message/FBMessageHandler.java
index 68772b7..e555416 100644
--- a/src/main/java/com/meta/cp4m/message/FBMessageHandler.java
+++ b/src/main/java/com/meta/cp4m/message/FBMessageHandler.java
@@ -44,7 +44,7 @@ public class FBMessageHandler implements MessageHandler<FBMessage> {
   private final String appSecret;
 
   private final String accessToken;
-  private final String owningPageID;
+  @Nullable private final String owningPageID;
 
   private final Deduplicator<Identifier> messageDeduplicator = new Deduplicator<>(10_000);
   private Function<Identifier, URI> baseURLFactory =
@@ -63,7 +63,7 @@ public class FBMessageHandler implements MessageHandler<FBMessage> {
         }
       };
 
-  public FBMessageHandler(String verifyToken, String pageAccessToken, String appSecret, String owningPageID) {
+  public FBMessageHandler(String verifyToken, String pageAccessToken, String appSecret, @Nullable String owningPageID) {
     this.verifyToken = verifyToken;
     this.appSecret = appSecret;
     this.accessToken = pageAccessToken;
@@ -74,7 +74,7 @@ public FBMessageHandler(String verifyToken, String pageAccessToken, String appSe
     this.verifyToken = verifyToken;
     this.appSecret = appSecret;
     this.accessToken = pageAccessToken;
-    this.owningPageID = "-1";
+    this.owningPageID = null;
   }
 
   FBMessageHandler(FBMessengerConfig config) {
@@ -220,7 +220,7 @@ private void send(String message, Identifier recipient, Identifier sender) throw
     try {
       bodyString = MAPPER.writeValueAsString(body);
       url =
-          new URIBuilder(baseURLFactory.apply(owningPageID.equals("-1") ? sender : Identifier.from(owningPageID)))
+          new URIBuilder(baseURLFactory.apply(owningPageID == null ? sender : Identifier.from(owningPageID)))
               .addParameter("access_token", accessToken)
               .build();
     } catch (JsonProcessingException | URISyntaxException e) {
diff --git a/src/main/java/com/meta/cp4m/message/FBMessengerConfig.java b/src/main/java/com/meta/cp4m/message/FBMessengerConfig.java
index 6ebc8d2..7ab7878 100644
--- a/src/main/java/com/meta/cp4m/message/FBMessengerConfig.java
+++ b/src/main/java/com/meta/cp4m/message/FBMessengerConfig.java
@@ -10,6 +10,7 @@
 
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.Optional;
 import java.util.UUID;
@@ -20,6 +21,7 @@ public class FBMessengerConfig implements HandlerConfig {
     private final String verifyToken;
     private final String appSecret;
     private final String pageAccessToken;
+    @Nullable
     private final String owningPageID;
 
     private FBMessengerConfig(
@@ -27,7 +29,7 @@ private FBMessengerConfig(
             @JsonProperty("verify_token") String verifyToken,
             @JsonProperty("app_secret") String appSecret,
             @JsonProperty("page_access_token") String pageAccessToken,
-            @JsonProperty("owning_page_id") String owningPageID) {
+            @JsonProperty("owning_page_id") @Nullable String owningPageID) {
 
         Preconditions.checkArgument(name != null && !name.isBlank(), "name cannot be blank");
         Preconditions.checkArgument(
@@ -41,10 +43,10 @@ private FBMessengerConfig(
         this.verifyToken = verifyToken;
         this.appSecret = appSecret;
         this.pageAccessToken = pageAccessToken;
-        this.owningPageID = owningPageID == null || owningPageID.isBlank() ? "-1" : owningPageID;
+        this.owningPageID = owningPageID;
     }
 
-    public static FBMessengerConfig of(String verifyToken, String appSecret, String pageAccessToken, String owningPageID) {
+    public static FBMessengerConfig of(String verifyToken, String appSecret, String pageAccessToken, @Nullable String owningPageID) {
         // human readability of the name only matters when it's coming from a config
         return new FBMessengerConfig(
                 UUID.randomUUID().toString(), verifyToken, appSecret, pageAccessToken, owningPageID);
@@ -53,7 +55,7 @@ public static FBMessengerConfig of(String verifyToken, String appSecret, String
     public static FBMessengerConfig of(String verifyToken, String appSecret, String pageAccessToken) {
         // human readability of the name only matters when it's coming from a config
         return new FBMessengerConfig(
-                UUID.randomUUID().toString(), verifyToken, appSecret, pageAccessToken, "-1");
+                UUID.randomUUID().toString(), verifyToken, appSecret, pageAccessToken, null);
     }
 
     @Override