diff --git a/lab04.c b/lab04.c
index b46690d..9cd095a 100644
--- a/lab04.c
+++ b/lab04.c
@@ -95,6 +95,9 @@ void execute_r_instruction(r_instruction* instruct) {
             registers[instruct->rd] =
                 registers[instruct->rs] | registers[instruct->rt];
             break;
+        case NOR_FUNC:
+            registers[instruct->rd] =
+                ~(registers[instruct->rs] | registers[instruct->rt]);
         default:
             fprintf(stderr, "Invalid function code!\n");
             exit(EXIT_FAILURE);