diff --git a/clip.cpp b/clip.cpp
index cce490d4..3ed65157 100644
--- a/clip.cpp
+++ b/clip.cpp
@@ -1229,11 +1229,20 @@ static void feature_out(std::vector<tile_feature> const &features, mvt_layer &ou
 										auto out_attr = numeric_out_field.find(outkey);
 										if (out_attr == numeric_out_field.end()) {
 											// not present at all, so copy our value to the prefixed output
+											numeric_out_field.emplace(prefixed, full_keys.size());
+											full_keys.push_back(prefixed);
+											full_values.push_back(mvt_value_to_serial_val(val));
 										} else {
 											// exists unprefixed, so copy it, and then accumulate on our value
+											numeric_out_field.emplace(prefixed, full_keys.size());
+											full_keys.push_back(prefixed);
+											full_values.push_back(full_values[out_attr->second]);
+
+											preserve_attribute(op.second, prefixed, mvt_value_to_serial_val(val), full_keys, full_values, attribute_accum_state);
 										}
 									} else {
 										// exists, so accumulate on our value
+										preserve_attribute(op.second, prefixed, mvt_value_to_serial_val(val), full_keys, full_values, attribute_accum_state);
 									}
 								}
 							}
diff --git a/tests/pbf/13-1310-3166.pbf.json b/tests/pbf/13-1310-3166.pbf.json
index bcfbc286..4c6b161a 100644
--- a/tests/pbf/13-1310-3166.pbf.json
+++ b/tests/pbf/13-1310-3166.pbf.json
@@ -4,14 +4,14 @@
 ] }
 ,
 { "type": "FeatureCollection", "properties": { "layer": "ne_10m_populated_places", "version": 2, "extent": 4096 }, "features": [
-{ "type": "Feature", "properties": { "SCALERANK": 1, "NATSCALE": 300, "LABELRANK": 1, "FEATURECLA": "Populated place", "NAME": "San Francisco", "NAMEALT": "San Francisco-Oakland", "NAMEASCII": "San Francisco", "ADM0CAP": 0, "WORLDCITY": 1, "MEGACITY": 1, "SOV0NAME": "United States", "SOV_A3": "USA", "ADM0NAME": "United States of America", "ADM0_A3": "USA", "ADM1NAME": "California", "ISO_A2": "US", "LATITUDE": 37.769196, "LONGITUDE": -122.417169, "POP_MAX": 3450000, "POP_MIN": 732072, "POP_OTHER": 27400, "RANK_MAX": 12, "RANK_MIN": 11, "MEGANAME": "San Francisco-Oakland", "LS_NAME": "San Francisco1", "MAX_POP10": 988636, "MAX_POP20": 1130999, "MAX_POP50": 1371285, "MAX_POP300": 4561697, "MAX_POP310": 4561697, "MAX_NATSCA": 300, "MIN_AREAKM": 218, "MAX_AREAKM": 1748, "MIN_AREAMI": 84, "MAX_AREAMI": 675, "MIN_PERKM": 126, "MAX_PERKM": 755, "MIN_PERMI": 78, "MAX_PERMI": 469, "MIN_BBXMIN": -122.516667, "MAX_BBXMIN": -122.516667, "MIN_BBXMAX": -122.358333, "MAX_BBXMAX": -121.733333, "MIN_BBYMIN": 37.191667, "MAX_BBYMIN": 37.575, "MIN_BBYMAX": 37.816667, "MAX_BBYMAX": 38.041667, "MEAN_BBXC": -122.301354, "MEAN_BBYC": 37.622288, "TIMEZONE": "America/Los_Angeles", "UN_FID": 570, "POP1950": 1855, "POP1955": 2021, "POP1960": 2200, "POP1965": 2361, "POP1970": 2529, "POP1975": 2590, "POP1980": 2656, "POP1985": 2805, "POP1990": 2961, "POP1995": 3095, "POP2000": 3236, "POP2005": 3387, "POP2010": 3450, "POP2015": 3544, "POP2020": 3684, "POP2025": 3803, "POP2050": 3898, "MIN_ZOOM": 2.7, "WIKIDATAID": "Q62", "WOF_ID": 85922583, "CAPALT": 0, "NAME_EN": "San Francisco", "NAME_DE": "San Francisco", "NAME_ES": "San Francisco", "NAME_FR": "San Francisco", "NAME_PT": "São Francisco", "NAME_RU": "Сан-Франциско", "NAME_ZH": "旧金山", "NAME_AR": "سان فرانسيسكو", "NAME_BN": "সান ফ্রান্সিস্কো", "NAME_EL": "Σαν Φρανσίσκο", "NAME_HI": "सैन फ्रांसिस्को", "NAME_HU": "San Francisco", "NAME_ID": "San Francisco", "NAME_IT": "San Francisco", "NAME_JA": "サンフランシスコ", "NAME_KO": "샌프란시스코", "NAME_NL": "San Francisco", "NAME_PL": "San Francisco", "NAME_SV": "San Francisco", "NAME_TR": "San Francisco", "NAME_VI": "San Francisco", "NE_ID": 1159151479, "NAME_FA": "سان فرانسیسکو", "NAME_HE": "סן פרנסיסקו", "NAME_UK": "Сан-Франциско", "NAME_UR": "سان فرانسسکو", "NAME_ZHT": "舊金山", "GEONAMESID": 5391959 }, "geometry": { "type": "Point", "coordinates": [ -122.399583, 37.784249 ] } }
+{ "type": "Feature", "properties": { "FEATURECLA": "Populated place", "NAME": "San Francisco", "NAMEALT": "San Francisco-Oakland", "NAMEASCII": "San Francisco", "SOV0NAME": "United States", "SOV_A3": "USA", "ADM0NAME": "United States of America", "ADM0_A3": "USA", "ADM1NAME": "California", "ISO_A2": "US", "MEGANAME": "San Francisco-Oakland", "LS_NAME": "San Francisco1", "TIMEZONE": "America/Los_Angeles", "WIKIDATAID": "Q62", "NAME_EN": "San Francisco", "NAME_DE": "San Francisco", "NAME_ES": "San Francisco", "NAME_FR": "San Francisco", "NAME_PT": "São Francisco", "NAME_RU": "Сан-Франциско", "NAME_ZH": "旧金山", "NAME_AR": "سان فرانسيسكو", "NAME_BN": "সান ফ্রান্সিস্কো", "NAME_EL": "Σαν Φρανσίσκο", "NAME_HI": "सैन फ्रांसिस्को", "NAME_HU": "San Francisco", "NAME_ID": "San Francisco", "NAME_IT": "San Francisco", "NAME_JA": "サンフランシスコ", "NAME_KO": "샌프란시스코", "NAME_NL": "San Francisco", "NAME_PL": "San Francisco", "NAME_SV": "San Francisco", "NAME_TR": "San Francisco", "NAME_VI": "San Francisco", "NAME_FA": "سان فرانسیسکو", "NAME_HE": "סן פרנסיסקו", "NAME_UK": "Сан-Франциско", "NAME_UR": "سان فرانسسکو", "NAME_ZHT": "舊金山", "SCALERANK": 1, "NATSCALE": 300, "LABELRANK": 1, "ADM0CAP": 0, "WORLDCITY": 1, "MEGACITY": 1, "LATITUDE": 37.769196, "LONGITUDE": -122.417169, "POP_MAX": 3450000, "POP_MIN": 732072, "POP_OTHER": 27400, "RANK_MAX": 12, "RANK_MIN": 11, "MAX_POP10": 988636, "MAX_POP20": 1130999, "MAX_POP50": 1371285, "MAX_POP300": 4561697, "MAX_POP310": 4561697, "MAX_NATSCA": 300, "MIN_AREAKM": 218, "MAX_AREAKM": 1748, "MIN_AREAMI": 84, "MAX_AREAMI": 675, "MIN_PERKM": 126, "MAX_PERKM": 755, "MIN_PERMI": 78, "MAX_PERMI": 469, "MIN_BBXMIN": -122.516667, "MAX_BBXMIN": -122.516667, "MIN_BBXMAX": -122.358333, "MAX_BBXMAX": -121.733333, "MIN_BBYMIN": 37.191667, "MAX_BBYMIN": 37.575, "MIN_BBYMAX": 37.816667, "MAX_BBYMAX": 38.041667, "MEAN_BBXC": -122.301354, "MEAN_BBYC": 37.622288, "UN_FID": 570, "POP1950": 1855, "POP1955": 2021, "POP1960": 2200, "POP1965": 2361, "POP1970": 2529, "POP1975": 2590, "POP1980": 2656, "POP1985": 2805, "POP1990": 2961, "POP1995": 3095, "POP2000": 3236, "POP2005": 3387, "POP2010": 3450, "POP2015": 3544, "POP2020": 3684, "POP2025": 3803, "POP2050": 3898, "MIN_ZOOM": 2.7, "WOF_ID": 85922583, "CAPALT": 0, "NE_ID": 1159151479, "GEONAMESID": 5391959 }, "geometry": { "type": "Point", "coordinates": [ -122.399583, 37.784249 ] } }
 ] }
 ,
 { "type": "FeatureCollection", "properties": { "layer": "ne_10m_roads", "version": 2, "extent": 4096 }, "features": [
-{ "type": "Feature", "properties": { "scalerank": 4, "featurecla": "Road", "type": "Major Highway", "sov_a3": "USA", "edited": "New in version 2.0.0", "name": "101", "question": 0, "length_km": 11, "toll": 0, "ne_part": "ne_1d4_original", "labelrank": 0, "ignore": 0, "add": 0, "rwdb_rd_id": 0, "orig_fid": 0, "uident": 118705, "continent": "North America", "expressway": 1, "level": "Federal", "min_zoom": 4, "min_label": 7 }, "geometry": { "type": "LineString", "coordinates": [ [ -122.407351, 37.767933 ], [ -122.412586, 37.781841 ], [ -122.419496, 37.788760 ] ] } }
+{ "type": "Feature", "properties": { "featurecla": "Road", "type": "Major Highway", "sov_a3": "USA", "edited": "New in version 2.0.0", "name": "101", "ne_part": "ne_1d4_original", "continent": "North America", "level": "Federal", "scalerank": 4, "question": 0, "length_km": 11, "toll": 0, "labelrank": 0, "ignore": 0, "add": 0, "rwdb_rd_id": 0, "orig_fid": 0, "uident": 118705, "expressway": 1, "min_zoom": 4, "min_label": 7 }, "geometry": { "type": "LineString", "coordinates": [ [ -122.407351, 37.767933 ], [ -122.412586, 37.781841 ], [ -122.419496, 37.788760 ] ] } }
 ,
-{ "type": "Feature", "properties": { "scalerank": 3, "featurecla": "Road", "type": "Major Highway", "sov_a3": "USA", "edited": "New in version 2.0.0", "name": "80", "question": 0, "length_km": 14, "toll": 1, "ne_part": "ne_1d4_original", "labelrank": 0, "ignore": 0, "add": 0, "rwdb_rd_id": 0, "orig_fid": 0, "uident": 311505, "continent": "North America", "expressway": 1, "level": "Interstate", "min_zoom": 3, "min_label": 6 }, "geometry": { "type": "LineString", "coordinates": [ [ -122.407351, 37.767933 ], [ -122.388253, 37.785300 ], [ -122.386837, 37.786453 ] ] } }
+{ "type": "Feature", "properties": { "featurecla": "Road", "type": "Major Highway", "sov_a3": "USA", "edited": "New in version 2.0.0", "name": "80", "ne_part": "ne_1d4_original", "continent": "North America", "level": "Interstate", "scalerank": 3, "question": 0, "length_km": 14, "toll": 1, "labelrank": 0, "ignore": 0, "add": 0, "rwdb_rd_id": 0, "orig_fid": 0, "uident": 311505, "expressway": 1, "min_zoom": 3, "min_label": 6 }, "geometry": { "type": "LineString", "coordinates": [ [ -122.407351, 37.767933 ], [ -122.388253, 37.785300 ], [ -122.386837, 37.786453 ] ] } }
 ,
-{ "type": "Feature", "properties": { "scalerank": 4, "featurecla": "Road", "type": "Major Highway", "sov_a3": "USA", "edited": "New in version 2.0.0", "name": "280", "question": 0, "length_km": 52, "toll": 0, "ne_part": "ne_1d4_original", "labelrank": 0, "ignore": 0, "add": 0, "rwdb_rd_id": 0, "orig_fid": 0, "uident": 124805, "continent": "North America", "expressway": 1, "level": "Interstate", "min_zoom": 4, "min_label": 7 }, "geometry": { "type": "LineString", "coordinates": [ [ -122.405677, 37.752665 ], [ -122.407351, 37.767933 ] ] } }
+{ "type": "Feature", "properties": { "featurecla": "Road", "type": "Major Highway", "sov_a3": "USA", "edited": "New in version 2.0.0", "name": "280", "ne_part": "ne_1d4_original", "continent": "North America", "level": "Interstate", "scalerank": 4, "question": 0, "length_km": 52, "toll": 0, "labelrank": 0, "ignore": 0, "add": 0, "rwdb_rd_id": 0, "orig_fid": 0, "uident": 124805, "expressway": 1, "min_zoom": 4, "min_label": 7 }, "geometry": { "type": "LineString", "coordinates": [ [ -122.405677, 37.752665 ], [ -122.407351, 37.767933 ] ] } }
 ] }
 ] }