diff --git a/src/mame/drivers/klax.cpp b/src/mame/drivers/klax.cpp
index 98590a8f486..527d86b2525 100644
--- a/src/mame/drivers/klax.cpp
+++ b/src/mame/drivers/klax.cpp
@@ -42,7 +42,7 @@ void klax_state::update_interrupts()
 void klax_state::scanline_update(screen_device &screen, int scanline)
 {
 	/* generate 32V signals */
-	if ((scanline & 32) == 0 && !(ioport("P1")->read() & 0x800))
+	if ((scanline & 32) == 0 && !(m_p1->read() & 0x800))
 		scanline_int_gen(m_maincpu);
 }
 
diff --git a/src/mame/includes/klax.h b/src/mame/includes/klax.h
index d94cccd0714..dc70f771cd5 100644
--- a/src/mame/includes/klax.h
+++ b/src/mame/includes/klax.h
@@ -13,22 +13,31 @@ class klax_state : public atarigen_state
 {
 public:
 	klax_state(const machine_config &mconfig, device_type type, const char *tag)
-		: atarigen_state(mconfig, type, tag),
-			m_playfield_tilemap(*this, "playfield"),
-			m_mob(*this, "mob")  { }
+		: atarigen_state(mconfig, type, tag)
+		, m_playfield_tilemap(*this, "playfield")
+		, m_mob(*this, "mob")
+		, m_p1(*this, "P1")
+	{ }
 
+	DECLARE_MACHINE_START(klax);
+	DECLARE_MACHINE_RESET(klax);
+
+	virtual void scanline_update(screen_device &screen, int scanline) override;
+
+	virtual void update_interrupts() override;
+	DECLARE_WRITE16_MEMBER(interrupt_ack_w);
+
+	DECLARE_WRITE16_MEMBER(klax_latch_w);
+
+	DECLARE_VIDEO_START(klax);
+	TILE_GET_INFO_MEMBER(get_playfield_tile_info);
+	UINT32 screen_update_klax(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect);
+
+	static const atari_motion_objects_config s_mob_config;
+
+private:
 	required_device<tilemap_device> m_playfield_tilemap;
 	required_device<atari_motion_objects_device> m_mob;
 
-	virtual void update_interrupts() override;
-	virtual void scanline_update(screen_device &screen, int scanline) override;
-	DECLARE_WRITE16_MEMBER(interrupt_ack_w);
-	TILE_GET_INFO_MEMBER(get_playfield_tile_info);
-	DECLARE_MACHINE_START(klax);
-	DECLARE_MACHINE_RESET(klax);
-	DECLARE_VIDEO_START(klax);
-	UINT32 screen_update_klax(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect);
-	DECLARE_WRITE16_MEMBER( klax_latch_w );
-
-	static const atari_motion_objects_config s_mob_config;
+	required_ioport	m_p1;
 };