diff --git a/src/main.rs b/src/main.rs
index d603601..b9b6a23 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -55,42 +55,28 @@ fn verify_code(codes : &Vec<(u32, u32)>) -> Result<(), String> {
         let op_code = (first_code >> 28) as u8;
         match op_code {
             0x0 | 0x1 |0x2 => {
-                if search_code {
-                    if first_code & 0xf000000 != 0x8000000 {
-                        return Err(format!("wrong code at line {}: need search code after search", line));
-                    }
-                    search_code = false
-                }
                 if pos + 2 > max_len {
                     return Err(format!("wrong code at line {}: unexpected end", line));
                 }
                 pos += 2;
             }
             0x4 => {
-                if search_code {
-                    if first_code & 0xf000000 != 0x8000000 {
-                        return Err(format!("wrong code at line {}: need search code after search", line));
-                    }
-                    search_code = false
-                }
                 if pos + 4 > max_len {
                     return Err(format!("wrong code at line {}: unexpected end", line));
                 }
+                let next_code = codes[pos + 2].1;
+                if next_code & 0xf0000000 != 0x40000000 {
+                    return Err(format!("serial code error at line {}: should start with 0x4", line + 1));
+                }
                 pos += 4;
             }
             0x5 => {
-                if search_code {
-                    return Err(format!("wrong code at line {}: need search code after search", line));
-                }
                 if pos + 4 > max_len {
                     return Err(format!("wrong code at line {}: unexpected end", line));
                 }
                 pos += 4;
             }
             0x8 => {
-                if search_code {
-                    return Err(format!("wrong code at line {}: need search code after search", line));
-                }
                 let search_bytes = (first_code & 0xffff) as usize;
                 if search_bytes == 0 {
                     return Err(format!("wrong code at line {}: search length should not be 0", line));
@@ -104,9 +90,6 @@ fn verify_code(codes : &Vec<(u32, u32)>) -> Result<(), String> {
                 pos += code_len;
             }
             0xa => {
-                if search_code {
-                    return Err(format!("wrong code at line {}: need search code after search", line));
-                }
                 if pos + 1 >= max_len {
                     return Err(format!("wrong code at line {}: unexpected end", line));
                 }
@@ -204,7 +187,14 @@ fn apply_code(patch_file : &str, codes : &Vec<(u32, u32)>) -> Result<(), String>
             0x4 => {
                 code_len = 4;
                 let mut val = codes[pos + 1].1;
-                let mut addr = (first_code & 0xffffff) as usize;
+                let mut addr = if (first_code & 0xf000000) >= 0x8000000 {
+                    if search_addr == None {
+                        continue;
+                    }
+                    (first_code & 0xffffff) as usize + search_addr.unwrap()
+                } else {
+                    (first_code & 0xffffff) as usize
+                };
                 let mut count = (codes[pos + 2].1 & 0xfff0000) >> 16;
                 let addr_diff = codes[pos + 2].1 & 0xffff;
                 let val_diff = codes[pos + 3].1;