diff --git a/CHANGELOG.md b/CHANGELOG.md
index d10ee6e..de857e5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -21,6 +21,7 @@
 ### Enhancements
 
 - Add python 3.13 to list of supported versions ([#158](https://github.com/mpytools/mplotutils/pull/158)).
+- Increased test coverage ([#180](https://github.com/mpytools/mplotutils/pull/180)).
 
 ### Bug fixes
 
diff --git a/mplotutils/__init__.py b/mplotutils/__init__.py
index ae5abf7..37f547b 100644
--- a/mplotutils/__init__.py
+++ b/mplotutils/__init__.py
@@ -46,7 +46,7 @@
 
 try:
     __version__ = _get_version("mplotutils")
-except Exception:
+except Exception:  # pragma: no cover
     # Local copy or not installed with setuptools.
     # Disable minimum version checks on downstream libraries.
     __version__ = "999"
diff --git a/mplotutils/_colorbar.py b/mplotutils/_colorbar.py
index ab0fcba..3fab597 100644
--- a/mplotutils/_colorbar.py
+++ b/mplotutils/_colorbar.py
@@ -237,7 +237,7 @@ def colorbar(
         raise ValueError(msg)
 
     if not all(isinstance(ax, mpl.axes.Axes) for ax in axs):
-        raise TypeError("ax must be of Type mpl.axes.Axes")
+        raise TypeError("ax must be of type mpl.axes.Axes")
 
     f = axs[0].get_figure()
 
diff --git a/mplotutils/tests/test_colorbar.py b/mplotutils/tests/test_colorbar.py
index fad7174..89f4270 100644
--- a/mplotutils/tests/test_colorbar.py
+++ b/mplotutils/tests/test_colorbar.py
@@ -144,6 +144,16 @@ def test_colorbar_deprecate_ax1():
             mpu.colorbar(h, ax1=ax)
 
 
+def test_colorbar_error_not_axes():
+
+    with pytest.raises(TypeError, match="ax must be of type mpl.axes.Axes"):
+        mpu.colorbar(None, object())
+
+    with figure_context() as f:
+        with pytest.raises(TypeError, match="ax must be of type mpl.axes.Axes"):
+            mpu.colorbar(None, f)
+
+
 def test_colorbar_different_figures():
     with figure_context() as f1, figure_context() as f2:
         ax1 = f1.subplots()
diff --git a/mplotutils/tests/test_hatch.py b/mplotutils/tests/test_hatch.py
index 2490994..bd50f19 100644
--- a/mplotutils/tests/test_hatch.py
+++ b/mplotutils/tests/test_hatch.py
@@ -57,7 +57,7 @@ def test_hatch_pattern(self):
 
             h = self.function(da, "*", ax=ax)
             assert h.hatches == ["", "*"]
-            h = self.function(da, "//", ax=ax)
+            h = self.function(da, "//")
             assert h.hatches == ["", "//"]
 
     def test_hatch_label(self):
diff --git a/mplotutils/tests/test_label_map.py b/mplotutils/tests/test_label_map.py
index a56776e..342d31e 100644
--- a/mplotutils/tests/test_label_map.py
+++ b/mplotutils/tests/test_label_map.py
@@ -9,3 +9,6 @@ def test_works():
     with subplots_context() as (f, ax):
         ylabel_map("ylabel", ax=ax)
         xlabel_map("ylabel", ax=ax)
+
+        ylabel_map("ylabel")
+        xlabel_map("ylabel")
diff --git a/mplotutils/tests/test_mapticklabels.py b/mplotutils/tests/test_mapticklabels.py
index 4eb4b74..9afd569 100644
--- a/mplotutils/tests/test_mapticklabels.py
+++ b/mplotutils/tests/test_mapticklabels.py
@@ -1,18 +1,21 @@
 import cartopy.crs as ccrs
 import numpy as np
+import pytest
 
 import mplotutils as mpu
 
 from . import subplots_context
 
 
-def test_yticklabels_robinson():
+@pytest.mark.parametrize("pass_ax", (True, False))
+def test_yticklabels_robinson(pass_ax):
     with subplots_context(subplot_kw=dict(projection=ccrs.Robinson())) as (f, ax):
         ax.set_global()
 
         lat = np.arange(-90, 91, 20)
 
-        mpu.yticklabels(lat, ax=ax, size=8)
+        ax_ = ax if pass_ax else None
+        mpu.yticklabels(lat, ax=ax_, size=8)
 
         x_pos = -179.99
 
@@ -47,13 +50,14 @@ def test_yticklabels_robinson_180():
         assert ax.texts[-1].get_text() == "70°N"
 
 
-def test_xticklabels_robinson():
+@pytest.mark.parametrize("pass_ax", (True, False))
+def test_xticklabels_robinson(pass_ax):
     with subplots_context(subplot_kw=dict(projection=ccrs.Robinson())) as (f, ax):
         ax.set_global()
 
         lon = np.arange(-180, 181, 60)
-
-        mpu.xticklabels(lon, ax=ax, size=8)
+        ax_ = ax if pass_ax else None
+        mpu.xticklabels(lon, ax=ax_, size=8)
 
         y_pos = -89.99