diff --git a/include/instructions.h b/include/instructions.h
index b140ad9..4145748 100644
--- a/include/instructions.h
+++ b/include/instructions.h
@@ -40,6 +40,7 @@ public:
   void sub_r32_rm32();  // 0x2b
   void sub_eax_imm32(); // 0x2d
   void xor_rm32_r32();  // 0x31
+  void xor_r32_rm32();  // 0x33
   void inc_eax();       // 0x40
   void inc_ecx();       // 0x41
   void inc_edx();       // 0x42
diff --git a/instructions.cpp b/instructions.cpp
index 160ed6b..4967084 100644
--- a/instructions.cpp
+++ b/instructions.cpp
@@ -33,6 +33,7 @@ void Instructions::init_instructions(){
   this->instructions[0x2b] = &Instructions::sub_r32_rm32;
   this->instructions[0x2d] = &Instructions::sub_eax_imm32;
   this->instructions[0x31] = &Instructions::xor_rm32_r32;
+  this->instructions[0x33] = &Instructions::xor_r32_rm32;
   this->instructions[0x40] = &Instructions::inc_eax;
   this->instructions[0x41] = &Instructions::inc_ecx;
   this->instructions[0x42] = &Instructions::inc_edx;
@@ -581,6 +582,56 @@ void Instructions::xor_rm32_r32(){
   }
 }
 
+void Instructions::xor_r32_rm32(){
+  //printf("xor_r32_rm32 called.\n");
+  uint32_t addr, dst, imm32;
+  uint8_t imm8;
+
+  this->modrm = memory.read_uint8(this->eip);
+  this->calc_modrm();
+
+  switch (this->mod) {
+    case 0:
+      // xor R, [M]
+      // addr : M
+      this->eip++;
+      addr = this->registers[this->M];
+      // dst : data of [M]
+      dst = memory.read_uint32(addr);
+      this->registers[this->R] ^= dst;
+      break;
+    case 1:
+      // xor R, [M+imm8]
+      this->eip++;
+      imm8 = memory.read_uint8(this->eip);
+      // addr : M
+      addr = this->registers[this->M];
+      // dst : data of [M+imm8]
+      dst = memory.read_uint32(addr + imm8);
+      this->registers[this->R] ^= dst;
+      this->eip++;
+      break;
+    case 2:
+      // xor R, [M+imm32]
+      this->eip++;
+      imm32 = memory.read_uint32(this->eip);
+      imm32 = swap_endian32(imm32);
+      // addr : M
+      addr = this->registers[this->M];
+      // dst : data of [M+imm32]
+      dst = memory.read_uint32(addr + imm32);
+      this->registers[this->R] ^= dst;
+      this->eip += 4;
+      break;
+    default:
+      // case mod == 3
+      // xor R, M
+      this->eip++;
+      this->registers[this->R] ^= this->registers[this->M];
+      break;
+  }
+}
+
 void Instructions::inc_eax(){
   //printf("inc_eax called.\n");
   this->registers[0]++;