diff --git a/src/decode.rs b/src/decode.rs
index 80ac041..43e04fa 100644
--- a/src/decode.rs
+++ b/src/decode.rs
@@ -1,5 +1,5 @@
 pub struct Instruction {
-    pub value : u64,
+    pub value : u32,
 
     pub opcode : u8, 
     pub rs1 : u8, 
@@ -26,7 +26,7 @@ pub struct Instruction {
     pub imm21_1_signed : i32,
 }
 
-pub fn decode(val : u64) -> Instruction {
+pub fn decode(val : u32) -> Instruction {
 
     let value = val;