diff --git a/hw/rtl/VX_ibuffer.v b/hw/rtl/VX_ibuffer.v
index 8c6a4d08..b94eead8 100644
--- a/hw/rtl/VX_ibuffer.v
+++ b/hw/rtl/VX_ibuffer.v
@@ -109,8 +109,10 @@ module VX_ibuffer #(
 
     // schedule the next instruction to issue
     always @(*) begin
-        deq_valid_n = 1;
         if (num_warps > 1) begin
+            deq_valid_n = 1;
+            deq_wid_n   = 'x;        
+            deq_instr_n = 'x;
             for (integer i = 0; i < `NUM_WARPS; i++) begin
                 if (schedule_table[i]) begin
                     deq_wid_n   = `NW_BITS'(i);                
@@ -119,6 +121,7 @@ module VX_ibuffer #(
                 end
             end
         end else if (1 == num_warps && !(deq_fire && q_alm_empty[deq_wid])) begin
+            deq_valid_n = 1;
             deq_wid_n   = deq_wid;
             deq_instr_n = deq_fire ? q_data_prev[deq_wid] : q_data_out[deq_wid];
         end else begin
diff --git a/hw/rtl/VX_scoreboard.v b/hw/rtl/VX_scoreboard.v
index 6b161a1f..cca7c007 100644
--- a/hw/rtl/VX_scoreboard.v
+++ b/hw/rtl/VX_scoreboard.v
@@ -14,7 +14,7 @@ module VX_scoreboard  #(
 
     reg is_reg_busy;
     always @(*) begin
-        is_reg_busy = 0;
+        is_reg_busy = 'x;
         for (integer i = 0; i < `NUM_WARPS; ++i) begin
             if (ibuf_deq_if.wid == `NW_BITS'(i)) begin
                 is_reg_busy = | (inuse_regs[i] & ibuf_deq_if.used_regs);