diff --git a/8086_sim/sim86.cpp b/8086_sim/sim86.cpp
index 3a63360..5a57241 100644
--- a/8086_sim/sim86.cpp
+++ b/8086_sim/sim86.cpp
@@ -49,6 +49,7 @@ int main(int argc, char *argv[]) {
   instruction_table table;
   Sim86_Get8086InstructionTable(&table);
 
+  u32 mem_start = size + 1;
   u32 offset = 0;
 
   bool accessed_registers[REGISTER_COUNT] = {false};