diff --git a/include/instructions.h b/include/instructions.h
index 895b62c..ee813b5 100644
--- a/include/instructions.h
+++ b/include/instructions.h
@@ -5,9 +5,12 @@
 #include "memory.h"
 #include "utils.h"
 
+const uint32_t ZF = 1 << 6;
+
 class Instructions{
 private:
   void init_instructions();
+  void set_flag(int flag, uint32_t flag_type);
 public:
   Memory memory;
   uint32_t registers[8];        // eax, ecx, edx, ebx, esp, ebp, esi, edi
diff --git a/instructions.cpp b/instructions.cpp
index a166212..54b0a7d 100644
--- a/instructions.cpp
+++ b/instructions.cpp
@@ -251,3 +251,11 @@ void Instructions::opcode_ff(){
       break;
   }
 }
+
+void Instructions::set_flag(int flag, uint32_t flag_type){
+  if (flag) {
+    this->eflags &= ~flag_type;
+  } else {
+    this->eflags |= flag_type;
+  }
+}