diff --git a/mach/i86/ncg/mach.h b/mach/i86/ncg/mach.h
index 311f0917a..fe958271f 100644
--- a/mach/i86/ncg/mach.h
+++ b/mach/i86/ncg/mach.h
@@ -12,7 +12,7 @@
 #define newilb(x)       fprintf(codefile,"%s:\n",x)
 #define newdlb(x)       fprintf(codefile,"%s:\n",x)
 #define dlbdlb(x,y)     fprintf(codefile,"%s = %s\n",x,y)
-#define newlbss(l,x)    fprintf(codefile,".comm %s,%d\n",l,x);
+#define newlbss(l,x)    fprintf(codefile,".comm %s,%u\n",l,x);
 
 #define cst_fmt         "%d"
 #define off_fmt         "%d"