diff --git a/include/instructions.h b/include/instructions.h
index e3366a5..490d914 100644
--- a/include/instructions.h
+++ b/include/instructions.h
@@ -108,5 +108,7 @@ public:
   void hlt();           // 0xf4
   void opcode_ff();     // 0xff
 
-  void cmp_rm32_imm8(); // called by opcode_83
+  // called by opcode_83
+  void add_rm32_imm8();
+  void cmp_rm32_imm8();
 };
diff --git a/instructions.cpp b/instructions.cpp
index c4c4908..a3d5540 100644
--- a/instructions.cpp
+++ b/instructions.cpp
@@ -1164,6 +1164,9 @@ void Instructions::opcode_83(){
   this->calc_modrm();
 
   switch (this->R) {
+    case 0:
+      add_rm32_imm8();
+      break;
     case 7:
       cmp_rm32_imm8();
       break;
@@ -1420,6 +1423,17 @@ void Instructions::opcode_ff(){
   }
 }
 
+void Instructions::add_rm32_imm8(){
+  //printf("add_rm32_imm8 called.\n");
+
+  this->eip++;
+  uint8_t imm8 = memory.read_uint8(this->eip);
+  //printf("imm8: 0x%08x (%d)\n", imm8, imm8);
+  this->registers[this->M] += imm8;
+
+  this->eip++;
+}
+
 void Instructions::cmp_rm32_imm8(){
   //printf("cmp_rm32_imm8 called.\n");