diff --git a/lib/regex_internal.c b/lib/regex_internal.c
index 7f0083b91..0b5f47317 100644
--- a/lib/regex_internal.c
+++ b/lib/regex_internal.c
@@ -409,6 +409,7 @@ build_wcs_upper_buffer (re_string_t *pstr)
 		    if (pstr->offsets == NULL)
 		      {
 			pstr->offsets = re_malloc (Idx, pstr->bufs_len);
+			memset (pstr->offsets, 0xBC, sizeof(Idx)*pstr->bufs_len);
 
 			if (pstr->offsets == NULL)
 			  return REG_ESPACE;