diff --git a/src/mess/drivers/xerox820.c b/src/mess/drivers/xerox820.c
index cff0d608b41..114bee250ca 100644
--- a/src/mess/drivers/xerox820.c
+++ b/src/mess/drivers/xerox820.c
@@ -69,8 +69,8 @@ void xerox820ii_state::bankswitch(int bank)
 	if (bank)
 	{
 		/* ROM */
-		program.install_rom(0x0000, 0x17ff, m_rom->base());
-		program.unmap_readwrite(0x1800, 0x2fff);
+		program.install_rom(0x0000, 0x1fff, m_rom->base());
+		program.unmap_readwrite(0x2000, 0x2fff);
 		program.install_ram(0x3000, 0x3fff, m_video_ram);
 		program.unmap_readwrite(0x4000, 0xbfff);
 	}
diff --git a/src/mess/includes/xerox820.h b/src/mess/includes/xerox820.h
index d1b92383e7c..8de4a25daac 100644
--- a/src/mess/includes/xerox820.h
+++ b/src/mess/includes/xerox820.h
@@ -97,7 +97,7 @@ public:
 	DECLARE_WRITE_LINE_MEMBER( fdc_intrq_w );
 	DECLARE_WRITE_LINE_MEMBER( fdc_drq_w );
 
-	void bankswitch(int bank);
+	virtual void bankswitch(int bank);
 	void update_nmi();
 
 	/* video state */