diff --git a/src/reassemble.html b/src/reassemble.html
index 14507b6..21abe49 100644
--- a/src/reassemble.html
+++ b/src/reassemble.html
@@ -119,7 +119,7 @@
             const firstMessage = document.getElementById('firstMessage').value.trim();
             const lines = firstMessage.split('\n');
             
-            if (lines.length < 2) {
+            if (lines.length < 3) {
                 alert('Invalid format for the first message.');
                 return;
             }
@@ -156,7 +156,7 @@
             const firstMessage = document.getElementById('firstMessage').value.trim();
             const lines = firstMessage.split('\n');
             
-            if (lines.length < 2) {
+            if (lines.length < 3) {
                 alert('Invalid format for the first message.');
                 return;
             }
diff --git a/src/splitter.html b/src/splitter.html
index 2bb9e31..63d5110 100644
--- a/src/splitter.html
+++ b/src/splitter.html
@@ -110,22 +110,24 @@
                     const hashArray = Array.from(new Uint8Array(hashBuffer));
                     const hashHex = hashArray.map(byte => byte.toString(16).padStart(2, '0')).join('');
                     
-                    // Prepare the prefix for the first chunk
-                    const firstChunkPrefix = `Hash: ${hashHex}\nMessage 1/`;
-                    const firstChunkContentSize = maxChunkSize - firstChunkPrefix.length - (String(text.length).length + 2);
+                    // Calculate the total number of chunks
+                    const totalChunks = Math.ceil(text.length / (maxChunkSize - 20)) + 1; // Considering extra space for prefixes
+
+                    // Prepare the first chunk with hash and sequence
+                    const firstChunkPrefix = `Hash: ${hashHex}\nMessage 1/${totalChunks}\n\n`;
+                    const firstChunkContentSize = maxChunkSize - firstChunkPrefix.length;
                     const firstChunk = firstChunkPrefix + text.substring(0, firstChunkContentSize);
-                    
+
                     // Add the first chunk to the list
                     chunks.push(firstChunk);
 
                     // Split the remaining text into chunks
-                    for (let i = firstChunkContentSize; i < text.length; i += maxChunkSize) {
-                        let chunk = text.substring(i, i + maxChunkSize);
-                        let chunkNumber = Math.floor(i / maxChunkSize) + 2; // Start from the second chunk
-                        let totalChunks = Math.ceil(text.length / maxChunkSize) + 1;
-                        let prefix = `Message ${chunkNumber}/${totalChunks}`;
+                    for (let i = firstChunkContentSize; i < text.length; i += maxChunkSize - 20) {
+                        let chunk = text.substring(i, i + (maxChunkSize - 20));
+                        let chunkNumber = Math.floor(i / (maxChunkSize - 20)) + 2; // Start from the second chunk
+                        let prefix = `Message ${chunkNumber}/${totalChunks}\n\n`;
                         
-                        chunk = `${prefix}\n\n${chunk}`;
+                        chunk = `${prefix}${chunk}`;
                         chunks.push(chunk);
                     }