diff --git a/src/instructions.c b/src/instructions.c
index 91fb36c..398f99c 100644
--- a/src/instructions.c
+++ b/src/instructions.c
@@ -24,12 +24,12 @@ instruction_t parse_inst(u_int8_t *binary, unsigned long size)
 }
 
 const instruction_t instructions[] = {
-	{.opcode = 0x00, .extended = -1, .name = "add", .mode = {R_M8, REG8, END}, .exec = NULL},
-	{.opcode = 0x01, .extended = -1, .name = "add", .mode = {R_M16, REG16, END}, .exec = NULL},
-	{.opcode = 0x02, .extended = -1, .name = "add", .mode = {REG8, R_M8, END}, .exec = NULL},
-	{.opcode = 0x03, .extended = -1, .name = "add", .mode = {REG16, R_M16, END}, .exec = NULL},
-	{.opcode = 0x04, .extended = -1, .name = "add", .mode = {OPREG8, IMM8, END}, .exec = NULL},
-	{.opcode = 0x05, .extended = -1, .name = "add", .mode = {OPREG16, IMM16, END}, .exec = NULL},
+	{.opcode = 0x00, .extended = -1, .name = "add", .mode = {R_M8, REG8, END}, .exec = &add},
+	{.opcode = 0x01, .extended = -1, .name = "add", .mode = {R_M16, REG16, END}, .exec = &add},
+	{.opcode = 0x02, .extended = -1, .name = "add", .mode = {REG8, R_M8, END}, .exec = &add},
+	{.opcode = 0x03, .extended = -1, .name = "add", .mode = {REG16, R_M16, END}, .exec = &add},
+	{.opcode = 0x04, .extended = -1, .name = "add", .mode = {OPREG8, IMM8, END}, .exec = &add},
+	{.opcode = 0x05, .extended = -1, .name = "add", .mode = {OPREG16, IMM16, END}, .exec = &add},
 	{.opcode = 0x06, .extended = -1, .name = "push es", .mode = {END}, .exec = &push},
 	{.opcode = 0x07, .extended = -1, .name = "pop es", .mode = {END}, .exec = NULL},
 	{.opcode = 0x08, .extended = -1, .name = "or", .mode = {R_M8, REG8, END}, .exec = NULL},
@@ -258,7 +258,7 @@ const instruction_t instructions[] = {
 const instruction_t extended[][8] = {
 	// 0x80 extended
 	{
-		{.opcode = 0x00, .extended = -2, .name = "add", .mode = {R_M8, IMM8, END}, .exec = NULL},
+		{.opcode = 0x00, .extended = -2, .name = "add", .mode = {R_M8, IMM8, END}, .exec = &add},
 		{.opcode = 0x01, .extended = -2, .name = "or", .mode = {R_M8, IMM8, END}, .exec = NULL},
 		{.opcode = 0x02, .extended = -2, .name = "adc", .mode = {R_M8, IMM8, END}, .exec = NULL},
 		{.opcode = 0x03, .extended = -2, .name = "sbb", .mode = {R_M8, IMM8, END}, .exec = NULL},
@@ -269,7 +269,7 @@ const instruction_t extended[][8] = {
 	},
 	// 0x81 extended
 	{
-		{.opcode = 0x00, .extended = -2, .name = "add", .mode = {R_M16, IMM16, END}, .exec = NULL},
+		{.opcode = 0x00, .extended = -2, .name = "add", .mode = {R_M16, IMM16, END}, .exec = &add},
 		{.opcode = 0x01, .extended = -2, .name = "or", .mode = {R_M16, IMM16, END}, .exec = NULL},
 		{.opcode = 0x02, .extended = -2, .name = "adc", .mode = {R_M16, IMM16, END}, .exec = NULL},
 		{.opcode = 0x03, .extended = -2, .name = "sbb", .mode = {R_M16, IMM16, END}, .exec = NULL},
@@ -280,7 +280,7 @@ const instruction_t extended[][8] = {
 	},
 	// 0x83 extended
 	{
-		{.opcode = 0x00, .extended = -2, .name = "add", .mode = {R_M16, IMM8, END}, .exec = NULL},
+		{.opcode = 0x00, .extended = -2, .name = "add", .mode = {R_M16, IMM8, END}, .exec = &add},
 		/**/{.opcode = 0x01, .extended = -2, .name = "invalid", .mode = {END}, .exec = NULL},
 		{.opcode = 0x02, .extended = -2, .name = "adc", .mode = {R_M16, IMM8, END}, .exec = NULL},
 		{.opcode = 0x03, .extended = -2, .name = "sbb", .mode = {R_M16, IMM8, END}, .exec = NULL},
diff --git a/src/instructions.h b/src/instructions.h
index 2f6b1f3..a37fd91 100644
--- a/src/instructions.h
+++ b/src/instructions.h
@@ -10,5 +10,6 @@ void jmp(const instruction_t *self, state_t *state);
 void int_inst(const instruction_t *self, state_t *state);
 void lea(const instruction_t *self, state_t *state);
 
+void add(const instruction_t *self, state_t *state);
 void sub(const instruction_t *self, state_t *state);
 void xor_inst(const instruction_t *self, state_t *state);
diff --git a/src/instructions/arithmetics.c b/src/instructions/arithmetics.c
index f7bc4a3..503d6de 100644
--- a/src/instructions/arithmetics.c
+++ b/src/instructions/arithmetics.c
@@ -2,6 +2,23 @@
 #include "../interpretor.h"
 #include <stdint.h>
 
+void add(const instruction_t *self, state_t *state)
+{
+	operand_t from = get_operand(self, 0, state);
+	operand_t to = get_operand(self, 1, state);
+	unsigned old = read_op(from);
+	unsigned minus = read_op(to);
+	unsigned value = old + minus;
+
+	write_op(from, value);
+
+	state->of = value != read_op(from);
+	state->cf = value >= (is_operand_wide(self, 0) ? 0x10000 : 0x100);
+	state->sf = value & (is_operand_wide(self, 0) ? 0x8000 : 0x80);
+	state->zf = value == 0;
+	// TODO: Set AF and PF
+}
+
 void sub(const instruction_t *self, state_t *state)
 {
 	operand_t from = get_operand(self, 0, state);