diff --git a/epan/dissectors/packet-per.c b/epan/dissectors/packet-per.c
index 2cf46f4422..a36db40c0c 100644
--- a/epan/dissectors/packet-per.c
+++ b/epan/dissectors/packet-per.c
@@ -685,6 +685,7 @@ DEBUG_ENTRY("dissect_per_restricted_character_string");
 			bits_per_char=8;
 		}
 	}
+
 	/* 27.4	If the type is extensible for PER encodings (see 9.3.16),
 	 * then a bit-field consisting of a single bit shall be added to the field-list.
 	 * The single bit shall be set to zero if the value is within the range of the extension root,
@@ -771,8 +772,8 @@ DEBUG_ENTRY("dissect_per_restricted_character_string");
 	}
 	str_len = (int)wmem_strbuf_get_len(buf);
 	str = wmem_strbuf_finalize(buf);
-	/* Note that str can contain embedded nulls */
-	proto_tree_add_string(tree, hf_index, tvb, (old_offset>>3), (offset>>3)-(old_offset>>3)+1, str);
+	/* Note that str can contain embedded nulls. Length claims any bytes partially used.  */
+	proto_tree_add_string(tree, hf_index, tvb, (old_offset>>3), ((offset+7)>>3)-(old_offset>>3), str);
 	if (value_tvb) {
 		*value_tvb = tvb_new_child_real_data(tvb, str, str_len, str_len);
 	}