diff --git a/CHANGELOG.md b/CHANGELOG.md
index fa60e6d..34a0b85 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,12 @@ and this project adheres to
 
 ## [Unreleased]
 
+### Fixed
+
+- The spelling bachelor thesis and master thesis are widely used but seem to be
+  wrong.  According to the Oxford English Dictionary, the spelling shall be
+  bachelor's thesis and master's thesis.
+
 ## [v4.2.0] – 2024–06–25
 
 ### Fixed
diff --git a/examples/se2thesis-master-thesis-example.pdf b/examples/se2thesis-master-thesis-example.pdf
index 703086b..1237a36 100644
Binary files a/examples/se2thesis-master-thesis-example.pdf and b/examples/se2thesis-master-thesis-example.pdf differ
diff --git a/se2thesis.dtx b/se2thesis.dtx
index 0a6705a..e982d16 100644
--- a/se2thesis.dtx
+++ b/se2thesis.dtx
@@ -62,7 +62,7 @@
 % internet, causing each thesis looking differently.
 %
 % The author of this package provided a template,
-% which he initially created for his bachelor and master thesis,
+% which he initially created for his bachelor's and master's thesis,
 % that was recommended and used by many students.
 % The implementation of that template, however, was very hacky and required
 % some changes over time.
@@ -243,9 +243,9 @@
 %   \end{syntax}
 %   Defines the type of the thesis.
 %   Possible values are:
-%   |bachelor| for a bachelor thesis, |bachelorproposal| for a proposal to
-%   a bachelor thesis, |master| for a master thesis, |masterproposal| for
-%   a proposal to a master thesis, |phdproposal| for a proposal to a PhD thesis,
+%   |bachelor| for a bachelor's thesis, |bachelorproposal| for a proposal to
+%   a bachelor's thesis, |master| for a master's thesis, |masterproposal| for
+%   a proposal to a master's thesis, |phdproposal| for a proposal to a PhD thesis,
 %   |phd| for a PhD thesis in the natural sciences, |phdeng| for a PhD thesis
 %   in engineering, and |phdphil| for a PhD thesis in natural philosophy.
 % \end{function}
@@ -307,7 +307,7 @@
 %     \cmd{\matrnumber} \marg{matriculation-number}
 %   \end{syntax}
 %   Specify the matriculation number of the student writing the thesis.
-%   This is required for Bachelor and Master theses.
+%   This is required for bachelor's and master's theses.
 % \end{function}
 %
 % \begin{function}{\supervisor, \cosupervisor}
@@ -437,7 +437,7 @@
 % We provide the \env{acknowledgements} environment to typeset acknowledgements
 % for your thesis.
 % Using this environment is optional.
-% Usually, bachelor and master thesis do not contain such an acknowledgements
+% Usually, bachelor's and master's thesis do not contain such an acknowledgements
 % section, however, there is no general rule to this.
 % \begin{verbatim}
 % \begin{acknowledgements}[language]
@@ -1246,7 +1246,7 @@
 %    \end{macrocode}
 %   The next block generates the text that describes the thesis.
 %   In case of a PhD thesis, this text is predefined to match the requirements.
-%   In case of a bachelor or master thesis, or a proposal thereof, we generate
+%   In case of a bachelor's or master's thesis, or a proposal thereof, we generate
 %   a text based on the values of the |thesistype| load-time option and the
 %   values of the \cmd{\degreeprogramme}, \cmd{\department}, and
 %   \cmd{\institute} variables.
@@ -1703,10 +1703,10 @@
 \ProvideDictTranslation{External}{External Examiner}
 \ProvideDictTranslation{degreeprogramme}{programme}
 \ProvideDictTranslation{Degreeprogramme}{Programme}
-\ProvideDictTranslation{Bachelor-thesis}{Bachelor Thesis}
-\ProvideDictTranslation{Bachelor-thesis-proposal}{Bachelor Thesis Proposal}
-\ProvideDictTranslation{Master-thesis}{Master Thesis}
-\ProvideDictTranslation{Master-thesis-proposal}{Master Thesis Proposal}
+\ProvideDictTranslation{Bachelor-thesis}{Bachelor's Thesis}
+\ProvideDictTranslation{Bachelor-thesis-proposal}{Bachelor's Thesis Proposal}
+\ProvideDictTranslation{Master-thesis}{Master's Thesis}
+\ProvideDictTranslation{Master-thesis-proposal}{Master's Thesis Proposal}
 \ProvideDictTranslation{PhD-thesis}{PhD Thesis}
 \ProvideDictTranslation{PhD-thesis-proposal}{PhD Thesis Proposal}
 \ProvideDictTranslation{date}{date}