diff --git a/lib/primitives/tx.js b/lib/primitives/tx.js
index b6606736..6e0349e8 100644
--- a/lib/primitives/tx.js
+++ b/lib/primitives/tx.js
@@ -719,7 +719,16 @@ class TX {
       }
     }
 
-    const size = 156 + prev.getVarSize();
+    // Calculate the extra floData size to add to the Buffer when initializing
+    let extraFloDataSize = 0
+    if (this.version >= 2 && includeFloData){
+      let bufferLength = this.floData.length;
+
+      extraFloDataSize += encoding.sizeVarint(bufferLength);
+      extraFloDataSize += bufferLength
+    }
+
+    const size = 156 + prev.getVarSize() + extraFloDataSize;
     const bw = bio.pool(size);
 
     bw.writeU32(this.version);