diff --git a/rtl/serv_decode.v b/rtl/serv_decode.v
index 30d80ac..6c8f1b1 100644
--- a/rtl/serv_decode.v
+++ b/rtl/serv_decode.v
@@ -167,8 +167,8 @@ module serv_decode
    //True for S (STORE) or B (BRANCH) type instructions
    //False for J type instructions
    assign o_immdec_ctrl[0] = opcode[3:0] == 4'b1000;
-   //True for OP-IMM, LOAD, STORE, JALR
-   //False for LUI, AUIPC, JAL
+   //True for OP-IMM, LOAD, STORE, JALR  (I S)
+   //False for LUI, AUIPC, JAL           (U J) 
    assign o_immdec_ctrl[1] = (opcode[1:0] == 2'b00) | (opcode[2:1] == 2'b00);
    assign o_immdec_ctrl[2] = opcode[4] & !opcode[0];
    assign o_immdec_ctrl[3] = opcode[4];