diff --git a/lib/cartopy/tests/mpl/test_axes.py b/lib/cartopy/tests/mpl/test_axes.py
index eaf5904b0f..4684137435 100644
--- a/lib/cartopy/tests/mpl/test_axes.py
+++ b/lib/cartopy/tests/mpl/test_axes.py
@@ -13,7 +13,7 @@
 
 import cartopy.crs as ccrs
 import cartopy.feature as cfeature
-from cartopy.mpl.geoaxes import InterProjectionTransform, GeoAxes
+from cartopy.mpl.geoaxes import InterProjectionTransform, GeoAxes, GeoAxesSubplot
 
 
 class TestNoSpherical:
@@ -119,7 +119,7 @@ def test_single_geometry(self):
 
 def test_geoaxes_subplot():
     ax = plt.subplot(1, 1, 1, projection=ccrs.PlateCarree())
-    assert str(ax.__class__) == "<class 'cartopy.mpl.geoaxes.GeoAxesSubplot'>"
+    assert isinstance(ax, GeoAxesSubplot)
 
 
 @pytest.mark.mpl_image_compare(filename='geoaxes_subslice.png')