diff --git a/tests/grib_g1monthlydate.sh b/tests/grib_g1monthlydate.sh
index 9441e60f6..cec628087 100755
--- a/tests/grib_g1monthlydate.sh
+++ b/tests/grib_g1monthlydate.sh
@@ -15,15 +15,19 @@ sample_g1=$ECCODES_SAMPLES_PATH/GRIB1.tmpl
 temp=temp.$label.grib
 
 ${tools_dir}/grib_set -s marsType=fc,marsStream=wamo $sample_g1 $temp
-
 grib_check_key_equals $temp "mars.date,monthlyVerificationDate" "20060301 20060301"
-
 ${tools_dir}/grib_dump $temp
 
+
 # Date as string with month names
+# --------------------------------
+# Year missing
 ${tools_dir}/grib_set -s yearOfCentury=255 $sample_g1 $temp
 grib_check_key_equals $temp "dataDate:s" "mar-16"
 
+# Year and day missing
+${tools_dir}/grib_set -s yearOfCentury=255,day=255 $sample_g1 $temp
+grib_check_key_equals $temp "dataDate:s" "mar"
 
 
 # Clean up