diff --git a/src/kafka-net/Common/Extensions.cs b/src/kafka-net/Common/Extensions.cs
index d7106e3f..730d634b 100644
--- a/src/kafka-net/Common/Extensions.cs
+++ b/src/kafka-net/Common/Extensions.cs
@@ -16,8 +16,10 @@ public static byte[] ToIntSizedBytes(this string value)
         {
             if (string.IsNullOrEmpty(value)) return (-1).ToBytes();
 
-            return value.Length.ToBytes()
-                        .Concat(value.ToBytes())
+            var bytes = value.ToBytes();
+
+            return bytes.Length.ToBytes()
+                        .Concat(bytes)
                         .ToArray();
         }
 
@@ -25,8 +27,10 @@ public static byte[] ToInt16SizedBytes(this string value)
         {
             if (string.IsNullOrEmpty(value)) return (-1).ToBytes();
 
-            return ((Int16)value.Length).ToBytes()
-                        .Concat(value.ToBytes())
+            var bytes = value.ToBytes();
+
+            return ((Int16)bytes.Length).ToBytes()
+                        .Concat(bytes)
                         .ToArray();
         }