diff --git a/django/contrib/gis/geos/prototypes/io.py b/django/contrib/gis/geos/prototypes/io.py
index efe9ec159f..05f597ccfc 100644
--- a/django/contrib/gis/geos/prototypes/io.py
+++ b/django/contrib/gis/geos/prototypes/io.py
@@ -156,7 +156,7 @@ class _WKTReader(IOBase):
 
     def read(self, wkt):
         if not isinstance(wkt, (bytes, str)):
-            raise TypeError
+            raise TypeError("'wkt' must be bytes or str.")
         return wkt_reader_read(self.ptr, force_bytes(wkt))
 
 
@@ -176,7 +176,7 @@ class _WKBReader(IOBase):
             wkb_s = wkb.encode()
             return wkb_reader_read_hex(self.ptr, wkb_s, len(wkb_s))
         else:
-            raise TypeError
+            raise TypeError("'wkb' must be bytes, str or memoryview.")
 
 
 def default_trim_value():
diff --git a/tests/gis_tests/geos_tests/test_io.py b/tests/gis_tests/geos_tests/test_io.py
index cab4b0ed5b..79ec3d053e 100644
--- a/tests/gis_tests/geos_tests/test_io.py
+++ b/tests/gis_tests/geos_tests/test_io.py
@@ -28,9 +28,10 @@ class GEOSIOTest(SimpleTestCase):
             self.assertEqual(ref, geom)
 
         # Should only accept string objects.
-        with self.assertRaises(TypeError):
+        msg = "'wkt' must be bytes or str."
+        with self.assertRaisesMessage(TypeError, msg):
             wkt_r.read(1)
-        with self.assertRaises(TypeError):
+        with self.assertRaisesMessage(TypeError, msg):
             wkt_r.read(memoryview(b"foo"))
 
     def test02_wktwriter(self):