diff --git a/libsrc/runtime/ladd.s b/libsrc/runtime/ladd.s
index fabedc9a1..a68583e76 100644
--- a/libsrc/runtime/ladd.s
+++ b/libsrc/runtime/ladd.s
@@ -8,14 +8,21 @@
 	.import		addysp1
 	.importzp	sp, sreg, tmp1
 
+        .macpack        cpu
+
 ; EAX = TOS + EAX
 
 tosaddeax:
-	ldy	#0
-	clc
-	adc	(sp),y	      	; byte 0
+      	clc
+.if (.cpu .bitand CPU_ISET_65SC02)
+     	adc	(sp)	       	; 65SC02 version - saves 2 cycles
+	ldy	#1
+.else
+      	ldy	#0
+      	adc	(sp),y		; lo byte
+      	iny
+.endif
 	sta    	tmp1 	      	; use as temp storage
-	iny
 	txa
 	adc	(sp),y	      	; byte 1
 	tax
diff --git a/libsrc/runtime/lsub.s b/libsrc/runtime/lsub.s
index 0ba716a9d..2ade75e2e 100644
--- a/libsrc/runtime/lsub.s
+++ b/libsrc/runtime/lsub.s
@@ -11,13 +11,20 @@
 	.import		addysp1
 	.importzp   	sp, sreg
 
+        .macpack        cpu
+
 tossubeax:
-      	ldy	#0
-       	sec
+      	sec
 	eor	#$FF
-       	adc	(sp),y		; byte 0
+.if (.cpu .bitand CPU_ISET_65SC02)
+     	adc	(sp)	       	; 65SC02 version - saves 2 cycles
+	ldy	#1
+.else
+      	ldy	#0
+      	adc	(sp),y	   	; lo byte
+      	iny
+.endif
        	pha			; Save low byte
-	iny
 	txa
 	eor	#$FF
 	adc	(sp),y		; byte 1
diff --git a/libsrc/runtime/popsreg.s b/libsrc/runtime/popsreg.s
index a79f9dc41..80e484339 100644
--- a/libsrc/runtime/popsreg.s
+++ b/libsrc/runtime/popsreg.s
@@ -1,5 +1,5 @@
 ;
-; Ullrich von Bassewitz, 21.08.1998
+; Ullrich von Bassewitz, 1998-08-21, 2009-02-22
 ;
 ; CC65 runtime: Pop TOS into sreg
 ;
@@ -8,15 +8,20 @@
 	.import		incsp2
        	.importzp	sp, sreg
 
+        .macpack        cpu
+
 popsreg:
    	pha	     		; save A
-   	ldy	#0
-   	lda	(sp),y		; get lo byte
-   	sta	sreg 		; store it
-   	iny
-   	lda	(sp),y		; get hi byte
+	ldy  	#1
+   	lda	(sp),y	   	; get hi byte
    	sta	sreg+1		; store it
+.if (.cpu .bitand ::CPU_ISET_65SC02)
+	lda	(sp)		; get lo byte
+.else
+   	dey
+   	lda	(sp),y		; get lo byte
+.endif
+   	sta	sreg 		; store it
    	pla	     		; get A back
    	jmp	incsp2		; bump stack and return
 
-
diff --git a/libsrc/runtime/stkchk.s b/libsrc/runtime/stkchk.s
index 40ccde3dc..ee0b7144c 100644
--- a/libsrc/runtime/stkchk.s
+++ b/libsrc/runtime/stkchk.s
@@ -21,6 +21,7 @@
 
 	; Use macros for better readability
 	.macpack	generic
+        .macpack        cpu
 
 
 ; ----------------------------------------------------------------------------
@@ -38,7 +39,11 @@
      	lda  	sp+1
      	sta  	initialsp+1
      	sbc  	#>__STACKSIZE__
-     	add  	#1	 		; Add 256 bytes safety area
+.if (.cpu .bitand ::CPU_ISET_65SC02)
+       	ina                     ; Add 256 bytes safety area
+.else
+       	add    	#1     	        ; Add 256 bytes safety area
+.endif
      	sta  	lowwater+1
      	rts