Insert the following polygon into a collection without an index. "type": "Polygon", "coordinates":[ [ [ -176.5573404206603, -26.62752545076926 ], [ -176.5790581155294, -26.45810909031957 ], [ -176.6707632150535, -25.96189875199764 ], [ -176.8290859572914, -25.15712799883819 ], [ -177.0482086728448, -24.07336864167018 ], [ -177.3200795588031, -22.75044410420587 ], [ -177.6347085473391, -21.23696608612408 ], [ -177.9805343970758, -19.58854829538924 ], [ -178.3448495182208, -17.86576288734291 ], [ -178.714266920998, -16.13191470250723 ], [ -179.0752121290624, -14.45071509014138 ], [ -179.4144219822276, -12.88394079437707 ], [ -179.7194319996838, -11.4891639286443 ], [ -179.9790343952361, -10.31763645191415 ], [ -180.1836899145046, -9.412406883018601 ], [ -180.3258783608655, -8.806738455571789 ], [ -180.4003749298368, -8.522886839391754 ], [ -180.4044421978278, -8.571282341822819 ], [ -180.3379307105011, -8.950146639488732 ], [ -180.2032844745671, -9.645558123911005 ], [ -180.0054511512106, -10.63196345982628 ], [ -179.7517002511473, -11.87311655866853 ], [ -179.4513560118511, -13.32341046404096 ], [ -179.1154547725442, -14.92955320820282 ], [ -178.7563394369255, -16.63252605916341 ], [ -178.38720592536, -18.36975220135411 ], [ -178.0216182824303, -20.07739616033413 ], [ -177.6730102575311, -21.69270947771339 ], [ -177.3541916732428, -23.15633644298238 ], [ -177.0768777202904, -24.41449515667321 ], [ -176.851258475444, -25.42095378030516 ], [ -176.685624460696, -26.13872935455922 ], [ -176.5860620027822, -26.54144676153235 ], [ -176.5573404206603, -26.62752545076926 ] ] ] } Then query the polygon using $geoIntersects. Everything works as expected. Then create an index on the field and add the same polygon you will get the following error "Can't extract geo keys from object, malformed geometry?" when inserted the same data. The polygon does pass the test on http://geojsonlint.com/