diff --git a/.gitignore b/.gitignore
index 23077b4..48bdc5a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -130,3 +130,6 @@ dmypy.json
 
 # PyCharm:
 .idea
+
+# vscode:
+.vscode
diff --git a/morecantile/models.py b/morecantile/models.py
index c43349c..f663a6c 100644
--- a/morecantile/models.py
+++ b/morecantile/models.py
@@ -40,7 +40,6 @@
 NumType = Union[float, int]
 BoundsType = Tuple[NumType, NumType]
 LL_EPSILON = 1e-11
-WGS84_CRS = pyproj.CRS.from_epsg(4326)
 axesInfo = Annotated[List[str], Field(min_length=2, max_length=2)]
 
 
@@ -697,6 +696,12 @@ def custom(
         TileMatrixSet
 
         """
+        geographic_crs = geographic_crs or crs.geodetic_crs
+        if not geographic_crs:
+            raise ValueError(
+                "CRS doesn't have internal geodeticCRS/geographicCRS defined, please provide one"
+            )
+
         matrix_scale = matrix_scale or [1, 1]
 
         if ordered_axes:
diff --git a/tests/test_models.py b/tests/test_models.py
index a62078b..c713a9f 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -6,6 +6,7 @@
 from collections.abc import Iterable
 
 import pyproj
+import pyproj.crs
 import pytest
 from pydantic import ValidationError
 from rasterio.crs import CRS as rioCRS
@@ -300,6 +301,22 @@ def test_zoom_for_res():
     assert tms.zoom_for_res(5000) == 6
 
 
+def test_custom_not_earth():
+    crs = pyproj.CRS.from_user_input("IAU_2015:49900")
+    extent = [-90, -180, 90, 180]
+    mars_tms = morecantile.TileMatrixSet.custom(extent, crs, id="MarsGeographicCRS")
+    assert "4326" not in mars_tms.geographic_crs.to_wkt()
+    assert "4326" not in mars_tms.rasterio_geographic_crs.to_wkt()
+    wkt_mars_web_mercator = 'PROJCRS["Mars (2015) - Sphere XY / Pseudo-Mercator",BASEGEOGCRS["Mars (2015) - Sphere",DATUM["Mars (2015) - Sphere",ELLIPSOID["Mars (2015) - Sphere",3396190,0,LENGTHUNIT["metre",1,ID["EPSG",9001]]],ANCHOR["Viking 1 lander : 47.95137 W"]],PRIMEM["Reference Meridian",0,ANGLEUNIT["degree",0.0174532925199433,ID["EPSG",9122]]]],CONVERSION["Popular Visualisation Pseudo-Mercator",METHOD["Popular Visualisation Pseudo Mercator",ID["EPSG",1024]],PARAMETER["Latitude of natural origin",0,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8801]],PARAMETER["Longitude of natural origin",0,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8802]],PARAMETER["False easting",0,LENGTHUNIT["metre",1],ID["EPSG",8806]],PARAMETER["False northing",0,LENGTHUNIT["metre",1],ID["EPSG",8807]]],CS[Cartesian,2],AXIS["easting (X)",east,ORDER[1],LENGTHUNIT["metre",1,ID["EPSG",9001]]],AXIS["northing (Y)",north,ORDER[2],LENGTHUNIT["metre",1,ID["EPSG",9001]]],USAGE[SCOPE["Web mapping and visualisation."],AREA["World between 85.06 S and 85.06 N."],BBOX[-85.850511287,-180,85.0511287,180]],REMARK["Use semi-major radius as sphere radius for interoperability. Source of IAU Coordinate systems: doi:10.1007/s10569-017-9805-5"]]'
+    crs_mars_web_mercator = pyproj.CRS.from_wkt(wkt_mars_web_mercator)
+    extent_wm = [-85.850511287, -180, 85.0511287, 180]
+    mars_tms_wm = morecantile.TileMatrixSet.custom(
+        extent_wm, crs_mars_web_mercator, id="MarsWebMercator"
+    )
+    assert "4326" not in mars_tms_wm.geographic_crs.to_wkt()
+    assert "4326" not in mars_tms_wm.rasterio_geographic_crs.to_wkt()
+
+
 def test_schema():
     """Translate Model to Schema."""
     tms = morecantile.tms.get("WebMercatorQuad")
@@ -316,7 +333,10 @@ def test_schema():
     assert tms.model_dump(exclude_none=True)
     json_doc = json.loads(tms.model_dump_json(exclude_none=True))
     assert json_doc["crs"] == "http://www.opengis.net/def/crs/IAU/2015/49930"
-
+    # test to ensure a correct geographic crs
+    mars_tms = TileMatrixSet.model_validate(json_doc)
+    assert "4326" not in mars_tms.geographic_crs.to_wkt()
+    assert "4326" not in mars_tms.rasterio_geographic_crs.to_wkt()
     crs = pyproj.CRS.from_epsg(3031)
     extent = [-948.75, -543592.47, 5817.41, -3333128.95]  # From https:///epsg.io/3031
     tms = morecantile.TileMatrixSet.custom(extent, crs, id="MyCustomTmsEPSG3031")