diff --git a/requirements.txt b/requirements.txt
index 71eba8d..653db6d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
 beautifulsoup4==4.11.2
-thothlibrary==0.17.0
+thothlibrary==0.26.0
 lxml==4.9.2
diff --git a/src/epublius/metadata.py b/src/epublius/metadata.py
index 3064c24..c1ff846 100644
--- a/src/epublius/metadata.py
+++ b/src/epublius/metadata.py
@@ -128,13 +128,15 @@ def get_chapter_title(self):
 
     def get_chapter_doi(self):
         '''
-        Retrieve chapter DOI based on the text of <p class=doi>
+        Retrieve chapter DOI based on the text of <p class="doi">
         (this contains both copyright statement and DOI link)
         '''
         # Not all chapters will have DOIs
         doi = None
 
-        doi_node = self.soup.find('p', class_='doi')
+        # Class string may not exactly match "doi" if an override has been implemented
+        # (e.g. `<p class="doi ParaOverride-9">`)
+        doi_node = self.soup.find('p', class_=lambda L: L and 'doi' in L.split())
 
         if (doi_node is not None):
             # In the case where multiple <a> elements are present,