diff --git a/benchmark.py b/benchmark.py
index d329e11..e9d8e1e 100644
--- a/benchmark.py
+++ b/benchmark.py
@@ -1,4 +1,4 @@
-from timeit import timeit, repeat
+from timeit import repeat, timeit
 
 from spans import *
 
@@ -28,10 +28,13 @@ def run_benchmark(func, number=None):
 
     total_time = sum(repeat(func, repeat=3, number=number)) / 3
 
-    print("{func:.<40} {loops} loops, best of 3: {per_loop} per loop".format(
-        func=func.__name__ + " ",
-        loops=number,
-        per_loop=format_sec(total_time / float(number))))
+    print(
+        "{func:.<40} {loops} loops, best of 3: {per_loop} per loop".format(
+            func=func.__name__ + " ",
+            loops=number,
+            per_loop=format_sec(total_time / float(number)),
+        )
+    )
 
 
 # Create ranges here to prevent __init__ from affecting test results
diff --git a/doc/conf.py b/doc/conf.py
index ac240d3..b2238d5 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -17,9 +17,9 @@
 
 # -- Project information -----------------------------------------------------
 
-project = 'Spans'
-copyright = '2022, Andreas Runfalk'
-author = 'Andreas Runfalk'
+project = "Spans"
+copyright = "2022, Andreas Runfalk"
+author = "Andreas Runfalk"
 
 
 # -- General configuration ---------------------------------------------------
@@ -33,12 +33,12 @@
 ]
 
 # Add any paths that contain templates here, relative to this directory.
-templates_path = ['_templates']
+templates_path = ["_templates"]
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
 # This pattern also affects html_static_path and html_extra_path.
-exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
+exclude_patterns = ["_build", "Thumbs.db", ".DS_Store"]
 
 
 # -- Options for HTML output -------------------------------------------------
@@ -46,9 +46,9 @@
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
 #
-html_theme = 'alabaster'
+html_theme = "alabaster"
 
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".
-html_static_path = ['_static']
+html_static_path = ["_static"]
diff --git a/doc/conftest.py b/doc/conftest.py
index 43a65e8..8c2780e 100644
--- a/doc/conftest.py
+++ b/doc/conftest.py
@@ -1,7 +1,9 @@
-import spans
+from datetime import date, datetime, timedelta
+
 import pytest
 
-from datetime import date, datetime, timedelta
+import spans
+
 
 @pytest.fixture(autouse=True)
 def doctest_fixture(doctest_namespace):
diff --git a/spans/__init__.py b/spans/__init__.py
index 588d786..666dbca 100644
--- a/spans/__init__.py
+++ b/spans/__init__.py
@@ -2,12 +2,12 @@
 This module provides one dimensional continuous set support for python.
 
 Python has a wonderful set class, it does however not handle continuous sets
-between two endpoints. This module tries to mitigate that. The ranges' behavoir
+between two endpoints. This module tries to mitigate that. The ranges' behavior
 are modeled after PostgresSQL 9.2's range types. Deviating from PostgresSQL's
-behavoir is considered a bug.
+behavior is considered a bug.
 
 In addition to the range types there are range sets. A range set is can be viewed
-as a mutable list of ranges. A set enables discontinious chunks to be grouped
+as a mutable list of ranges. A set enables discontinuous chunks to be grouped
 together.
 """
 
diff --git a/spans/types.py b/spans/types.py
index d1aae1c..0a6c941 100644
--- a/spans/types.py
+++ b/spans/types.py
@@ -124,7 +124,7 @@ def __init__(self, lower=None, upper=None, lower_inc=None, upper_inc=None):
 
         if upper is not None and not isinstance(upper, self.type):
             raise TypeError(
-                f"Invalid type for lower bound '{upper.__class__.__name__}'"
+                f"Invalid type for upper bound '{upper.__class__.__name__}'"
                 f" expected '{self.type.__name__}'"
             )
 
diff --git a/tests/test_range.py b/tests/test_range.py
index 41d590d..58df184 100644
--- a/tests/test_range.py
+++ b/tests/test_range.py
@@ -66,6 +66,11 @@ def test_invalid_construction(range_type, lower, upper, lower_inc, upper_inc, ex
         range_type(lower, upper, lower_inc, upper_inc)
 
 
+def test_invalid_upper_bound_message():
+    with pytest.raises(TypeError, match="upper bound"):
+        intrange(1, 1.5)
+
+
 @pytest.mark.parametrize(
     "range_type, lower, upper",
     [