diff --git a/system/registers.v b/system/registers.v
index 80552c4..4917af0 100644
--- a/system/registers.v
+++ b/system/registers.v
@@ -65,23 +65,23 @@ always @(negedge write_port1_we) begin
 	`ifdef DEBUG_REG_WRITES
 		if(write_port1_addr[3:2]==2'b11)begin
 			case(write_port1_addr[1:0])
-				2'b00: debug_name="sp";
-				2'b01: debug_name="bp";
-				2'b10: debug_name="si";
-				2'b11: debug_name="di";
+				2'b00: debug_name<="sp";
+				2'b01: debug_name<="bp";
+				2'b10: debug_name<="si";
+				2'b11: debug_name<="di";
 			endcase
 		end else begin
 			case(write_port1_addr[1:0])
-				2'b00: debug_name="ax";
-				2'b01: debug_name="cx";
-				2'b10: debug_name="dx";
-				2'b11: debug_name="bx";
+				2'b00: debug_name<="ax";
+				2'b01: debug_name<="cx";
+				2'b10: debug_name<="dx";
+				2'b11: debug_name<="bx";
 			endcase
 		end
 		if (write_Wbit)begin
 			$display("register %%%s update to $0x%04x",debug_name,registers[write_port1_addr[2:0]]);
 		end else begin
-			$display("register %%%s update to $0x%04x",debug_name,registers[write_port1_addr[1:0]]);
+			$display("register %%%s update to $0x%04x",debug_name,registers[{1'b0,write_port1_addr[1:0]}]);
 		end
 	`endif
 end