diff --git a/src/hw_ostc_parser.c b/src/hw_ostc_parser.c
index bf28be9..f377684 100644
--- a/src/hw_ostc_parser.c
+++ b/src/hw_ostc_parser.c
@@ -465,6 +465,8 @@ hw_ostc_parser_get_field (dc_parser_t *abstract, dc_field_type_t type, unsigned
 			*((double *) value) = array_uint16_le (data + layout->maxdepth) / 100.0;
 			break;
 		case DC_FIELD_AVGDEPTH:
+			if (parser->version < 0x21)
+				return DC_STATUS_UNSUPPORTED;
 			*((double *) value) = array_uint16_le (data + layout->avgdepth) / 100.0;
 			break;
 		case DC_FIELD_GASMIX_COUNT: