diff --git a/nvp.c b/nvp.c
index 04e2087..81aef8f 100644
--- a/nvp.c
+++ b/nvp.c
@@ -153,6 +153,7 @@ struct nvp *make_nvp(struct msg_src *src, char *s, const char *pfx)/*{{{*/
   struct nvp *result;
   size_t pfxlen;
   char *nn, *mm, *vv;
+  char *vv_null_pos;
 
   pfxlen = strlen(pfx);
   if (strncasecmp(pfx, s, pfxlen))
@@ -168,6 +169,7 @@ struct nvp *make_nvp(struct msg_src *src, char *s, const char *pfx)/*{{{*/
   nn = name;
   mm = minor;
   vv = value;
+  vv_null_pos = value + sizeof(value) - 1;
   last_action = GOT_NOTHING;
   do {
     qq = *(unsigned char *) q;
@@ -211,6 +213,7 @@ struct nvp *make_nvp(struct msg_src *src, char *s, const char *pfx)/*{{{*/
 #ifdef VERBOSE_TEST
         fprintf(stderr, "  COPY_TO_VALUE\n");
 #endif
+        if (vv < vv_null_pos)
         *vv++ = *q;
         break;
       case COPY_NOWHERE: