diff --git a/libsrc/atari/getargs.s b/libsrc/atari/getargs.s
index f8f247937..d2d7157ea 100644
--- a/libsrc/atari/getargs.s
+++ b/libsrc/atari/getargs.s
@@ -23,8 +23,10 @@ initmainargs:
 
 	lda	__dos_type	; which DOS?
 	cmp	#ATARIDOS
+	beq	nargdos		; DOS does not support arguments
+	cmp	#MYDOS
 	bne	argdos		; DOS supports arguments
-	rts
+nargdos:rts
 
 ; Initialize ourcl buffer
 
diff --git a/libsrc/atari/getdefdev.s b/libsrc/atari/getdefdev.s
index 249aeda60..8878f8060 100644
--- a/libsrc/atari/getdefdev.s
+++ b/libsrc/atari/getdefdev.s
@@ -25,6 +25,8 @@ _getdefdev:
 	lda	__dos_type	; which DOS?
 	cmp	#ATARIDOS
 	beq	finish
+	cmp	#MYDOS
+	beq	finish
 
 	ldy	#BUFOFF
 	lda	#0