diff --git a/pygmt/datasets/earth_free_air_anomaly.py b/pygmt/datasets/earth_free_air_anomaly.py
index df1154f2aaa..190f218d858 100644
--- a/pygmt/datasets/earth_free_air_anomaly.py
+++ b/pygmt/datasets/earth_free_air_anomaly.py
@@ -69,8 +69,9 @@ def load_earth_free_air_anomaly(
         higher than 5 arc-minutes (i.e., ``"05m"``).
     registration
         Grid registration type. Either ``"pixel"`` for pixel registration or
-        ``"gridline"`` for gridline registration. Default is ``None`` which means
-        ``"gridline"`` for all resolutions except ``"01m"`` which is ``"pixel"`` only.
+        ``"gridline"`` for gridline registration. Default is ``None``, which means
+        ``"gridline"`` for all resolutions except ``"01m"`` which is ``"pixel"``
+        only.
     uncertainty
         By default, the Earth free-air anomaly values are returned. Set to ``True`` to
         return the related uncertainties instead.
diff --git a/pygmt/datasets/earth_magnetic_anomaly.py b/pygmt/datasets/earth_magnetic_anomaly.py
index 70ffcf54248..463f7cf93b9 100644
--- a/pygmt/datasets/earth_magnetic_anomaly.py
+++ b/pygmt/datasets/earth_magnetic_anomaly.py
@@ -76,10 +76,10 @@ def load_earth_magnetic_anomaly(
         higher than 5 arc-minutes (i.e., ``"05m"``).
     registration
         Grid registration type. Either ``"pixel"`` for pixel registration or
-        ``"gridline"`` for gridline registration. Default is ``None``, means
+        ``"gridline"`` for gridline registration. Default is ``None``, which means
         ``"gridline"`` for all resolutions except ``"02m"`` for
-        ``data_source="emag2"`` or ``data_source="emag2_4km"``, which are
-        ``"pixel"`` only.
+        ``data_source="emag2"`` or ``data_source="emag2_4km"``, which are ``"pixel"``
+        only.
     data_source
         Select the source of the magnetic anomaly data. Available options are:
 
diff --git a/pygmt/datasets/earth_relief.py b/pygmt/datasets/earth_relief.py
index 3ff03613491..f0090ca3bd2 100644
--- a/pygmt/datasets/earth_relief.py
+++ b/pygmt/datasets/earth_relief.py
@@ -83,9 +83,9 @@ def load_earth_relief(
         higher than 5 arc-minutes (i.e., ``"05m"``).
     registration
         Grid registration type. Either ``"pixel"`` for pixel registration or
-        ``"gridline"`` for gridline registration. Default is ``None``, means
-        ``"gridline"`` for all resolutions except ``"15s"`` which is
-        ``"pixel"`` only.
+        ``"gridline"`` for gridline registration. Default is ``None``, which means
+        ``"gridline"`` for all resolutions except ``"15s"`` which is ``"pixel"``
+        only.
     data_source
         Select the source for the Earth relief data. Available options are:
 
diff --git a/pygmt/datasets/earth_vertical_gravity_gradient.py b/pygmt/datasets/earth_vertical_gravity_gradient.py
index 2ebba4563bc..bcf00099fc2 100644
--- a/pygmt/datasets/earth_vertical_gravity_gradient.py
+++ b/pygmt/datasets/earth_vertical_gravity_gradient.py
@@ -62,9 +62,9 @@ def load_earth_vertical_gravity_gradient(
         higher than 5 arc-minutes (i.e., ``"05m"``).
     registration
         Grid registration type. Either ``"pixel"`` for pixel registration or
-        ``"gridline"`` for gridline registration. Default is ``None``, means
-        ``"gridline"`` for all resolutions except ``"01m"`` which is
-        ``"pixel"`` only.
+        ``"gridline"`` for gridline registration. Default is ``None``, which means
+        ``"gridline"`` for all resolutions except ``"01m"`` which is ``"pixel"``
+        only.
 
     Returns
     -------
diff --git a/pygmt/datasets/mars_relief.py b/pygmt/datasets/mars_relief.py
index edfd8535210..e04f048d42f 100644
--- a/pygmt/datasets/mars_relief.py
+++ b/pygmt/datasets/mars_relief.py
@@ -75,7 +75,7 @@ def load_mars_relief(
         higher than 5 arc-minutes (i.e., ``"05m"``).
     registration
         Grid registration type. Either ``"pixel"`` for pixel registration or
-        ``"gridline"`` for gridline registration. Default is ``None``, means
+        ``"gridline"`` for gridline registration. Default is ``None``, which means
         ``"gridline"`` for all resolutions except for ``"12s"`` which is ``"pixel"``
         only.
 
diff --git a/pygmt/datasets/mercury_relief.py b/pygmt/datasets/mercury_relief.py
index 398ae65dd4d..06da8194e4a 100644
--- a/pygmt/datasets/mercury_relief.py
+++ b/pygmt/datasets/mercury_relief.py
@@ -73,7 +73,7 @@ def load_mercury_relief(
         higher than 5 arc-minutes (i.e., ``"05m"``).
     registration
         Grid registration type. Either ``"pixel"`` for pixel registration or
-        ``"gridline"`` for gridline registration. Default is ``None``, means
+        ``"gridline"`` for gridline registration. Default is ``None``, which means
         ``"gridline"`` for all resolutions except for ``"56s"`` which is ``"pixel"``
         only.
 
diff --git a/pygmt/datasets/moon_relief.py b/pygmt/datasets/moon_relief.py
index add30b0f051..66817f42d08 100644
--- a/pygmt/datasets/moon_relief.py
+++ b/pygmt/datasets/moon_relief.py
@@ -75,7 +75,7 @@ def load_moon_relief(
         higher than 5 arc-minutes (i.e., ``"05m"``).
     registration
         Grid registration type. Either ``"pixel"`` for pixel registration or
-        ``"gridline"`` for gridline registration. Default is ``None``, means
+        ``"gridline"`` for gridline registration. Default is ``None``, which means
         ``"gridline"`` for all resolutions except for ``"14s"`` which is ``"pixel"``
         only.
 
diff --git a/pygmt/datasets/pluto_relief.py b/pygmt/datasets/pluto_relief.py
index 224e89beb10..9a9998d228a 100644
--- a/pygmt/datasets/pluto_relief.py
+++ b/pygmt/datasets/pluto_relief.py
@@ -73,7 +73,7 @@ def load_pluto_relief(
         higher than 5 arc-minutes (i.e., ``"05m"``).
     registration
         Grid registration type. Either ``"pixel"`` for pixel registration or
-        ``"gridline"`` for gridline registration. Default is ``None``, means
+        ``"gridline"`` for gridline registration. Default is ``None``, which means
         ``"gridline"`` for all resolutions except for ``"52s"`` which is ``"pixel"``
         only.