diff --git a/.epubcheck.tsv b/.epubcheck.tsv
index 1aafab779..a538911ab 100644
--- a/.epubcheck.tsv
+++ b/.epubcheck.tsv
@@ -1,4 +1,5 @@
 HTM-049	WARNING
+HTM-054 WARNING
 RSC-005	WARNING
 RSC-007	WARNING
 RSC-012	WARNING
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 543755668..36096ecb4 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -17,7 +17,7 @@ env:
   DEFAULT_AGDA_STDLIB_VERSION: "2.1"
   DEFAULT_GHC_VERSION: "9.4.8"
   DEFAULT_CABAL_VERSION: "3.10.1.0"
-  DEFAULT_EPUBCHECK_VERSION: "4.2.6"
+  DEFAULT_EPUBCHECK_VERSION: "5.1.0"
   NOKOGIRI_USE_SYSTEM_LIBRARIES: true
 
 # Use PowerShell by default