diff --git a/libsrc/common/vsnprintf.s b/libsrc/common/vsnprintf.s
index 10dc7fa1d..21c358780 100644
--- a/libsrc/common/vsnprintf.s
+++ b/libsrc/common/vsnprintf.s
@@ -4,7 +4,7 @@
 ; Ullrich von Bassewitz, 2009-09-26
 ;
 
-   	.export	      	_vsnprintf
+   	.export	      	_vsnprintf, vsnprintf
  	.import	      	ldaxysp, popax, incsp2, incsp6
 	.import	      	_memcpy, __printf
 	.importzp     	sp, ptr1
@@ -26,6 +26,107 @@ bufsize:.word   0               ; Buffer size
 
 .code
 
+; ----------------------------------------------------------------------------
+; vsprintf - formatted output into a buffer
+;
+; int __fastcall__ vsnprintf (char* buf, size_t size, const char* format, va_list ap);
+;
+
+_vsnprintf:
+    	pha	   		; Save ap
+        txa
+        pha
+
+; Setup the outdesc structure. This is also an additional entry point for
+; vsprintf with ap on stack
+
+vsnprintf:
+    	lda	#0
+    	sta	ccount+0
+    	sta	ccount+1        ; Clear ccount
+
+; Get the size parameter and replace it by a pointer to outdesc. This is to
+; build a stack frame for the call to _printf.
+; If size is zero, there's nothing to do.
+
+        ldy     #2
+        lda     (sp),y
+        sta     ptr1
+
+        lda     #<outdesc
+        sta     (sp),y
+
+        iny
+        lda     (sp),y
+        sta     ptr1+1
+
+        ora     ptr1
+        beq     L9
+
+        lda     #>outdesc
+        sta     (sp),y
+
+; Write size-1 to outdesc.uns
+
+        ldy     ptr1+1
+        ldx     ptr1
+        bne     L1
+        dey
+L1:     dex
+        stx     bufsize+0
+        sty     bufsize+1
+
+; Copy buf to the outdesc.ptr
+
+        ldy     #5
+        jsr     ldaxysp
+        sta     bufptr+0
+        stx     bufptr+1
+
+; Restore ap and call _printf
+
+	pla
+        tax
+        pla
+	jsr	__printf
+
+; Terminate the string. The last char is either at bufptr+ccount or
+; bufptr+bufsize, whichever is smaller.
+
+        lda     ccount+0
+        ldx     ccount+1
+        cpx     bufsize+1
+        bne     L2
+        cmp     bufsize+0
+L2:     bcc     L3
+        lda     bufsize+0
+        ldx     bufsize+1
+        clc
+L3:     adc     bufptr+0
+        sta     ptr1
+        txa
+        adc     bufptr+1
+        sta     ptr1+1
+
+        lda     #0
+        tay
+        sta     (ptr1),y
+
+; Return the number of bytes written and drop buf
+
+        lda     ccount+0
+        ldx     ccount+1
+	jmp     incsp2
+
+; Bail out if size is zero.
+
+L9:     pla
+        pla                     ; Discard ap
+        lda     #0
+        tax
+        jmp     incsp6          ; Drop parameters
+
+
 ; ----------------------------------------------------------------------------
 ; Callback routine used for the actual output.
 ;
@@ -40,17 +141,17 @@ out:
 ; Calculate the space left in the buffer. If no space is left, don't copy
 ; any characters
 
-        lda     bufsize                 ; Low byte of buffer size
+        lda     bufsize+0               ; Low byte of buffer size
         sec
         sbc     ccount+0                ; Low byte of bytes already written
         sta     ptr1
         lda     bufsize+1
         sbc     ccount+1
         sta     ptr1+1
-        bcs     @L0                     ; Space left
-        lda     #0
+        bcs     @L0                     ; Branch if space left
+        lda     #$00
         sta     ptr1
-        sta     ptr1+1
+        sta     ptr1+1                  ; No space left
 
 ; Replace the pointer to d by a pointer to the write position in the buffer
 ; for the call to memcpy that follows.
@@ -95,92 +196,4 @@ out:
 @L2:    jmp     _memcpy
 
 
-; ----------------------------------------------------------------------------
-; vsprintf - formatted output into a buffer
-;
-; int __fastcall__ vsnprintf (char* buf, size_t size, const char* format, va_list ap);
-;
-
-_vsnprintf:
-    	pha	   		; Save low byte of ap
-
-; Setup the outdesc structure
-
-    	lda	#0
-    	sta	ccount+0
-    	sta	ccount+1        ; Clear ccount
-
-; Get the size parameter and replace it by a pointer to outdesc. This is to
-; build a stack frame for the call to _printf.
-; If size is zero, there's nothing to do.
-
-        ldy     #2
-        lda     (sp),y
-        sta     ptr1
-        lda     #<outdesc
-        sta     (sp),y
-        iny
-        lda     (sp),y
-        sta     ptr1+1
-        ora     ptr1
-        beq     L9
-
-        lda     #>outdesc
-        sta     (sp),y
-
-; Write size-1 to outdesc.uns
-
-        ldx     ptr1
-        ldy     ptr1+1
-        dex
-        bne     L1
-        dey
-L1:     stx     bufsize+0
-        sty     bufsize+1
-
-; Copy buf to the outdesc.ptr
-
-        ldy     #5
-        jsr     ldaxysp
-        sta     bufptr+0
-        stx     bufptr+1
-
-; Restore low byte of ap and call _printf
-
-	pla
-	jsr	__printf
-
-; Terminate the string
-
-        lda     ccount+0
-        ldx     ccount+1
-        cpx     bufsize+1
-        bne     L2
-        cmp     bufsize+0
-L2:     bcc     L3
-        lda     bufsize+0
-        ldx     bufsize+1
-        clc
-L3:     adc     bufptr+0
-        sta     ptr1
-        txa
-        adc     bufptr+1
-        sta     ptr1+1
-
-        lda     #0
-        tay
-        sta     (ptr1),y
-
-; Return the number of bytes written and drop buf
-
-        lda     ccount+0
-        ldx     ccount+1
-	jmp     incsp2
-
-; Bail out if size is zero
-
-L9:     lda     #0
-        tax
-        jmp     incsp6          ; Drop parameters
-
 
diff --git a/libsrc/common/vsprintf.s b/libsrc/common/vsprintf.s
index 4c265ec22..f1a2fe5d8 100644
--- a/libsrc/common/vsprintf.s
+++ b/libsrc/common/vsprintf.s
@@ -4,9 +4,9 @@
 ; Ullrich von Bassewitz, 2009-09-26
 ;
 
-   	.export	      	_vsprintf
-	.import	      	pushw0sp, staxysp
-	.import	      	_vsnprintf
+   	.export	       	_vsprintf
+	.import	       	pushw0sp, staxysp
+	.import	       	vsnprintf
 
 
 ; ----------------------------------------------------------------------------
@@ -30,10 +30,8 @@ _vsprintf:
         ldy     #2
         jsr     staxysp
 
-; Retrieve ap and contine by jumping to _vsnprintf, which will cleanup the stack
+; Contine by jumping to vsnprintf, which expects ap on the CPU stack and will 
+; cleanup the C stack
 
-        pla
-        tax
-        pla
-        jmp     _vsnprintf
+        jmp     vsnprintf