diff --git a/kernel/kernel/PIC.cpp b/kernel/kernel/PIC.cpp
index 8c68968f4..6c59d5912 100644
--- a/kernel/kernel/PIC.cpp
+++ b/kernel/kernel/PIC.cpp
@@ -1,30 +1,21 @@
-#include <kernel/PIC.h>
 #include <kernel/IDT.h>
 #include <kernel/IO.h>
+#include <kernel/PIC.h>
 
 #include <string.h>
 
-#define PIC1			0x20		/* IO base address for master PIC */
-#define PIC2			0xA0		/* IO base address for slave PIC */
-#define PIC1_COMMAND	PIC1
-#define PIC1_DATA		(PIC1+1)
-#define PIC2_COMMAND	PIC2
-#define PIC2_DATA		(PIC2+1)
+#define PIC1_CMD	0x20
+#define PIC1_DATA	0x21
+#define PIC2_CMD	0xA0
+#define PIC2_DATA	0xA1
 
-#define PIC_READ_ISR	0x0B
-#define PIC_EOI			0x20
+#define PIC_ISR		0x0B
+#define PIC_EOI		0x20
 
-#define ICW1_ICW4		0x01		/* ICW4 (not) needed */
-#define ICW1_SINGLE		0x02		/* Single (cascade) mode */
-#define ICW1_INTERVAL4	0x04		/* Call address interval 4 (8) */
-#define ICW1_LEVEL		0x08		/* Level triggered (edge) mode */
-#define ICW1_INIT		0x10		/* Initialization - required! */
- 
-#define ICW4_8086		0x01		/* 8086/88 (MCS-80/85) mode */
-#define ICW4_AUTO		0x02		/* Auto (normal) EOI */
-#define ICW4_BUF_SLAVE	0x08		/* Buffered mode/slave */
-#define ICW4_BUF_MASTER	0x0C		/* Buffered mode/master */
-#define ICW4_SFNM		0x10		/* Special fully nested (not) */
+#define ICW1_ICW4	0x01
+#define ICW1_INIT	0x10
+
+#define ICW4_8086	0x01
 
 PIC* PIC::create()
 {
@@ -39,9 +30,9 @@ void PIC::remap()
 	uint8_t a2 = IO::inb(PIC2_DATA);
 
 	// Start the initialization sequence (in cascade mode)
-	IO::outb(PIC1_COMMAND, ICW1_INIT | ICW1_ICW4);
+	IO::outb(PIC1_CMD, ICW1_INIT | ICW1_ICW4);
 	IO::io_wait();
-	IO::outb(PIC2_COMMAND, ICW1_INIT | ICW1_ICW4);
+	IO::outb(PIC2_CMD, ICW1_INIT | ICW1_ICW4);
 	IO::io_wait();
 
 	// ICW2
@@ -69,41 +60,37 @@ void PIC::remap()
 
 void PIC::mask_all()
 {
-	IO::outb(PIC1_DATA, 0xFF);
+	// NOTE: don't mask irq 2 as it is needed for slave pic
+	IO::outb(PIC1_DATA, 0xFB);
 	IO::outb(PIC2_DATA, 0xFF);
 }
 
 void PIC::eoi(uint8_t irq)
 {
 	if (irq >= 8)
-		IO::outb(PIC2_COMMAND, PIC_EOI);
-	IO::outb(PIC1_COMMAND, PIC_EOI);
+		IO::outb(PIC2_CMD, PIC_EOI);
+	IO::outb(PIC1_CMD, PIC_EOI);
 }
 
 void PIC::enable_irq(uint8_t irq)
 {
-	uint16_t port;
-	uint8_t value;
-
-	if(irq < 8)
-	{
-		port = PIC1_DATA;
-	}
-	else
+	uint16_t port = PIC1_DATA;
+	if(irq >= 8)
 	{
 		port = PIC2_DATA;
 		irq -= 8;
 	}
-	value = IO::inb(port) & ~(1 << irq);
-	IO::outb(port, value);
+	IO::outb(port, IO::inb(port) & ~(1 << irq));
 }
 
 bool PIC::is_in_service(uint8_t irq)
 {
-	uint16_t port = irq < 8 ? PIC1_COMMAND : PIC2_COMMAND;
-	uint8_t  bit  = irq < 8 ? irq : irq - 8;
-
-	IO::outb(port, PIC_READ_ISR);
-	uint16_t isr = IO::inb(port);
-	return isr & (1 << bit);
-}
\ No newline at end of file
+	uint16_t port = PIC1_CMD;
+	if (irq >= 8)
+	{
+		port = PIC2_CMD;
+		irq -= 8;
+	}
+	IO::outb(port, PIC_ISR);
+	return IO::inb(port) & (1 << irq);
+}