diff --git a/npc/Makefile b/npc/Makefile
index 54a4902..b1ea816 100644
--- a/npc/Makefile
+++ b/npc/Makefile
@@ -21,4 +21,4 @@ include ../Makefile
 .PHONY: clean 
 
 clean: 
-	$(RM) -r $(OBJDIR)
\ No newline at end of file
+	$(RM) -r $(OBJDIR)
diff --git a/npc/csrc/main.cpp b/npc/csrc/main.cpp
index 834439f..9f178e3 100644
--- a/npc/csrc/main.cpp
+++ b/npc/csrc/main.cpp
@@ -8,7 +8,7 @@ int main(int argc, char **argv, char **env) {
     Verilated::commandArgs(argc, argv);
     Vexample *top = new Vexample;
     int round = 100;
-    while (1) {
+    while (round--) {
         int a = rand() & 1;
         int b = rand() & 1;
         top->a = a;