diff --git a/libsrc/c64/get_ostype.s b/libsrc/c64/get_ostype.s
index e2db72ae2..4058e116e 100644
--- a/libsrc/c64/get_ostype.s
+++ b/libsrc/c64/get_ostype.s
@@ -1,6 +1,9 @@
 ;
 ; Stefan Haubenthal, Jul 10 2003
 ;
+; C64DTV detection by
+; Marco van den Heuvel, 2010-01-28
+;
 ; unsigned char get_ostype(void)
 ;
 ; $AA US
@@ -8,16 +11,33 @@
 ; $43 SX-64
 ; $03 EU_NEW
 ; $00 EU_OLD
+; $FF C64DTV
 ;
 
 	.export		_get_ostype
 
 .proc	_get_ostype
 
-        ldx     #$00            ; Clear high byte
-	lda	$ff80
+	ldx 	#0            ; Clear high byte
+
+       	ldy	#1
+	sty	$d03f
+	ldy	$d040
+	cpy	$d000
+	bne	@c64dtv
+	inc	$d000
+	cpy	$d040
+	beq	@c64dtv
+
+; Normal C64
+
+	lda 	$ff80
 	rts
 
+; C64 DTV
+
+@c64dtv:
+       	stx	$d03f
+	lda	#$ff
+	rts
 .endproc
-
-