--- ./src/cmd/ksh93/sh/name.c.orig	2019-04-04 14:28:17.044667686 +0000
+++ ./src/cmd/ksh93/sh/name.c	2019-04-04 14:28:32.472629455 +0000
@@ -1986,8 +1986,11 @@ void nv_putval(register Namval_t *np, co
 		up->cp = cp;
 		if(sp)
 		{
+			size_t splen = strlen(sp);
 			int c = cp[dot+append];
-			memmove(cp+append,sp,dot);
+			memmove(cp+append,sp,dot>splen?splen:dot);
+			if (dot>splen)
+				memset(cp+append+splen,0,dot-splen);
 			cp[dot+append] = c;
 			if(nv_isattr(np, NV_RJUST) && nv_isattr(np, NV_ZFILL))
 				rightjust(cp,size,'0');