diff --git a/system/registers.v b/system/registers.v
index a1ca666..33b6956 100644
--- a/system/registers.v
+++ b/system/registers.v
@@ -32,11 +32,11 @@ input write_port1_we;
 
 reg [15:0] registers [7:0];
 
-assign read_port1_data[15:8] = read_port1_addr[3:3] ? registers[read_port1_addr[2:0]][15:8] : 8'hz ;
+assign read_port1_data[15:8] = read_port1_addr[3:3] ? registers[read_port1_addr[2:0]][15:8] : 8'h0 ;
 assign read_port1_data[7:0] = ( read_port1_addr[3:3] ? registers[read_port1_addr[2:0]][7:0] :
 	( read_port1_addr[2:2] ? registers[ {1'b0,read_port1_addr[1:0]} ][15:8] : registers[ {1'b0,read_port1_addr[1:0]} ][7:0] ) );
 
-assign read_port2_data[15:8] = read_port2_addr[3:3] ? registers[read_port2_addr[2:0]][15:8] : 8'hz ;
+assign read_port2_data[15:8] = read_port2_addr[3:3] ? registers[read_port2_addr[2:0]][15:8] : 8'h0 ;
 assign read_port2_data[7:0] = ( read_port2_addr[3:3] ? registers[read_port2_addr[2:0]][7:0] :
 	( read_port2_addr[2:2] ? registers[ {1'b0,read_port2_addr[1:0]} ][15:8] : registers[ {1'b0,read_port2_addr[1:0]} ][7:0] ) );