diff --git a/src/backend/core/Mem.cpp b/src/backend/core/Mem.cpp
index 31db701..eadd4a8 100644
--- a/src/backend/core/Mem.cpp
+++ b/src/backend/core/Mem.cpp
@@ -9,7 +9,7 @@ namespace n64 {
 Mem::Mem() : flash(saveData) {
   rom.cart.resize(CART_SIZE);
   std::ranges::fill(rom.cart, 0);
-  isviewer_sink = std::ofstream("isviewer.log", std::ios::app);
+  isviewer_sink = std::ofstream("isviewer.log");
 }
 
 void Mem::Reset() {
diff --git a/src/backend/core/mmio/PI.cpp b/src/backend/core/mmio/PI.cpp
index 0963c26..9ece210 100644
--- a/src/backend/core/mmio/PI.cpp
+++ b/src/backend/core/mmio/PI.cpp
@@ -319,7 +319,7 @@ void PI::BusWrite<u32, false>(u32 addr, u32 val) {
     case CART_ISVIEWER_FLUSH:
       {
         if (val < CART_ISVIEWER_SIZE) {
-          std::string message(val + 1, 0);
+          std::string message(val, 0);
           std::copy_n(mem.isviewer.begin(), val, message.begin());
           mem.isviewer_sink << message;
           mem.isviewer_sink.flush();