diff --git a/libsrc/geos/common/memset.s b/libsrc/geos/common/memset.s
index e52437614..74005b0e9 100644
--- a/libsrc/geos/common/memset.s
+++ b/libsrc/geos/common/memset.s
@@ -1,21 +1,41 @@
 ;
 ; void* memset (void* ptr, int c, size_t n);
+; void* _bzero (void* ptr, size_t n);
+; void bzero (void* ptr, size_t n);
 ;
 ; Maciej 'YTM/Elysium' Witkowiak, 15.07.2001
 ;
+; NOTE: bzero will return it's first argument as memset does. It is no problem
+;       to declare the return value as void, since it may be ignored. _bzero
+;       (note the leading underscore) is declared with the proper return type,
+;       because the compiler will replace memset by _bzero if the fill value
+;       is zero, and the optimizer looks at the return type to see if the value
+;       in a/x is of any use.
 
- 	.export	_memset
+
+ 	.export	_memset, _bzero, __bzero
         .import popa, popax
 
         .include "../inc/jumptab.inc"
         .include "../inc/geossym.inc"
 
+_bzero:
+__bzero:
+	    sta r0L
+	    stx r0H
+    	    lda #0
+    	    sta r2L            ; fill with zeros
+	    beq common
+
 _memset:
 	    sta r0L
 	    stx r0H
 	    jsr popax
 	    sta r2L
-	    jsr popax
+common:	    jsr popax
 	    sta r1L
 	    stx r1H
-	    jmp FillRam
+	    jsr FillRam
+	    lda	r1L		; restore ptr and pass as result
+	    ldx r1H
+	    rts