diff --git a/harmony/harmony.py b/harmony/harmony.py
index fb7953d..5082064 100644
--- a/harmony/harmony.py
+++ b/harmony/harmony.py
@@ -151,16 +151,16 @@ def __repr__(self) -> str:
 
 
 class WKT:
-    """The WKT represntation of Spatial."""
+    """The Well Known Text (WKT) representation of Spatial."""
 
     def __init__(self, wkt: str):
-        """Constructs a WKT of spatial area.
+        """Constructs a WKT instance of spatial area.
 
         Args:
-            wkt: WKT string
+            wkt: the WKT string
 
         Returns:
-            A WKT
+            A WKT instance
         """
         self.wkt = wkt
 
@@ -382,7 +382,7 @@ def __init__(self,
                 'variables': 'parameter-name'
             }
             self.spatial_validations = [
-                (lambda s: is_wkt_valid(s.wkt), f'WKT {spatial.wkt} is not valid'),
+                (lambda s: is_wkt_valid(s.wkt), f'WKT {spatial.wkt} is invalid'),
             ]
         else:
             self.variable_name_to_query_param = {
diff --git a/tests/test_request.py b/tests/test_request.py
index 77ada83..7ad08f0 100644
--- a/tests/test_request.py
+++ b/tests/test_request.py
@@ -165,9 +165,9 @@ def test_request_dimensions_error_messages(value):
     assert message in messages
 
 @pytest.mark.parametrize('key, value, message', [
-    ('spatial', WKT('BBOX(-140,20,-50,60)'), 'WKT BBOX(-140,20,-50,60) is not valid'),
-    ('spatial', WKT('APOINT(0 51.48)'), 'WKT APOINT(0 51.48) is not valid'),
-    ('spatial', WKT('CIRCULARSTRING(0 0, 1 1, 1 0)'), 'WKT CIRCULARSTRING(0 0, 1 1, 1 0) is not valid'),
+    ('spatial', WKT('BBOX(-140,20,-50,60)'), 'WKT BBOX(-140,20,-50,60) is invalid'),
+    ('spatial', WKT('APOINT(0 51.48)'), 'WKT APOINT(0 51.48) is invalid'),
+    ('spatial', WKT('CIRCULARSTRING(0 0, 1 1, 1 0)'), 'WKT CIRCULARSTRING(0 0, 1 1, 1 0) is invalid'),
 ])
 def test_request_spatial_error_messages(key, value, message):
     request = Request(Collection('foo'), **{key: value})