diff --git a/lib/CPUs/MIPS/src/core/mips_instr.vhd b/lib/CPUs/MIPS/src/core/mips_instr.vhd
index cbfc588..3db27b9 100644
--- a/lib/CPUs/MIPS/src/core/mips_instr.vhd
+++ b/lib/CPUs/MIPS/src/core/mips_instr.vhd
@@ -157,7 +157,7 @@ package body mips_instr is
 		rt		:= to_integer(extract_rt(instr));
 		rs		:= to_integer(extract_rs(instr));
 		
-		result := op_sll;
+		result := reserved;
 		
 		case opc is
 
@@ -485,6 +485,7 @@ package body mips_instr is
 	variable result : ctrl_lines_t;
 	begin
 		result.cop_instr_en				:= '0';
+		result.cop_read					:= '0';
 		result.jump						:= '0';
 		result.jump_long				:= '0';
 		result.branch					:= '0';
@@ -794,6 +795,18 @@ package body mips_instr is
 --		when COPz =>
 		when 16 | 17 | 18 | 19 =>			
 			result.cop_instr_en		:= '1';
+			case rs is
+				when 0 =>	-- MFCz
+					result.cop_read		:= '1';
+					result.reg_write	:= '1';
+				when 2 =>	-- CFCz
+					result.cop_read		:= '1';
+					result.reg_write	:= '1';
+							
+				when others => null; -- undef
+			
+			end case;
+			
 			
 --		when op_addi =>
 		when 8 =>