diff --git a/libsrc/atari5200/y2k.inc b/libsrc/atari5200/y2k.inc
index a44d027a1..f8531451c 100644
--- a/libsrc/atari5200/y2k.inc
+++ b/libsrc/atari5200/y2k.inc
@@ -32,10 +32,8 @@ Y2K3    STA     $0732,X
         LDA     #$60            ; Store RTS opcode @ end
         STA     $0750
         JSR     $0600           ; Show title screen
-        LDY     #$00            ; Clear RAM from $0600-$3FFF
+        LDY     #<$0600         ; Clear RAM from $0600-$3FFF
         STY     $80
-        LDA     #$06
+        LDA     #>$0600
         STA     $81
-        JSR     CLRRAM
-        RTS     
-
+        JMP     CLRRAM
diff --git a/libsrc/common/strlen.s b/libsrc/common/strlen.s
index e89039179..8d5bc20fc 100644
--- a/libsrc/common/strlen.s
+++ b/libsrc/common/strlen.s
@@ -5,17 +5,27 @@
 ; the usage of only ptr2 here! Keep in mind when appling changes
 ; and check the other implementations too!
 ;
-; int strlen (const char* s);
+; size_t __fastcall__ strlen (const char* s);
 ;
 
         .export         _strlen
         .importzp       ptr2
+        .macpack        cpu
 
 _strlen:
         sta     ptr2            ; Save s
         stx     ptr2+1
+.if (.cpu .bitand ::CPU_ISET_HUC6280)
+        clx
+        cly
+.else
         ldx     #0              ; YX used as counter
+.if (.cpu .bitand ::CPU_ISET_65816)
+        txy
+.else
         ldy     #0
+.endif
+.endif
 
 L1:     lda     (ptr2),y
         beq     L9