diff --git a/Chatbase/Client.cs b/Chatbase/Client.cs
index e8c9b18..b2c6c5d 100644
--- a/Chatbase/Client.cs
+++ b/Chatbase/Client.cs
@@ -189,16 +189,16 @@ public async Task<HttpResponseMessage> Send(FBAgentMessageSet set)
 
         private Message setMessageWithClientProperties(Message msg)
         {
-            if (!String.IsNullOrEmpty(api_key)) {
+            if (!String.IsNullOrWhiteSpace(api_key)) {
                 msg.api_key = api_key;
             }
-            if (!String.IsNullOrEmpty(user_id)) {
+            if (!String.IsNullOrWhiteSpace(user_id)) {
                 msg.user_id = user_id;
             }
-            if (!String.IsNullOrEmpty(platform)) {
+            if (!String.IsNullOrWhiteSpace(platform)) {
                 msg.platform = platform;
             }
-            if (!String.IsNullOrEmpty(version)) {
+            if (!String.IsNullOrWhiteSpace(version)) {
                 msg.version = version;
             }
             
diff --git a/Chatbase/FBAgentMessage.cs b/Chatbase/FBAgentMessage.cs
index d4a8d2f..d8c4c8e 100644
--- a/Chatbase/FBAgentMessage.cs
+++ b/Chatbase/FBAgentMessage.cs
@@ -48,7 +48,7 @@ public class FBAgentMessage
 
         public bool RequiredFieldsSet()
         {
-          return !String.IsNullOrEmpty(api_key);
+          return !String.IsNullOrWhiteSpace(api_key);
         }
 
         public FBAgentMessage SetRecipientID(string id)
diff --git a/Chatbase/FBUserMessage.cs b/Chatbase/FBUserMessage.cs
index 0cddc19..2071306 100644
--- a/Chatbase/FBUserMessage.cs
+++ b/Chatbase/FBUserMessage.cs
@@ -57,10 +57,10 @@ public class FBUserMessage
         public bool RequiredFieldsSet()
         {
           return !(
-              String.IsNullOrEmpty(sender.id)
-              || String.IsNullOrEmpty(recipient.id)
-              || String.IsNullOrEmpty(message.mid)
-              || String.IsNullOrEmpty(api_key)
+              String.IsNullOrWhiteSpace(sender.id)
+              || String.IsNullOrWhiteSpace(recipient.id)
+              || String.IsNullOrWhiteSpace(message.mid)
+              || String.IsNullOrWhiteSpace(api_key)
           );
         }
 
diff --git a/Chatbase/Message.cs b/Chatbase/Message.cs
index 0a2d110..61fe01d 100755
--- a/Chatbase/Message.cs
+++ b/Chatbase/Message.cs
@@ -68,10 +68,10 @@ public static double CurrentUnixMilliseconds()
         public bool RequiredFieldsSet()
         {
             return !(
-                String.IsNullOrEmpty(api_key)
-                || String.IsNullOrEmpty(type)
-                || String.IsNullOrEmpty(user_id)
-                || String.IsNullOrEmpty(platform)
+                String.IsNullOrWhiteSpace(api_key)
+                || String.IsNullOrWhiteSpace(type)
+                || String.IsNullOrWhiteSpace(user_id)
+                || String.IsNullOrWhiteSpace(platform)
             );
         }