diff --git a/CHANGES.md b/CHANGES.md
index e7f260803..d9e2817a1 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,11 @@
 # Changes
 
+## 3.12.0 (2025-10-XX)
+
+Development:
+
+- Upgrade from Unicode 16 to Unicode 17. (#585)
+
 ## 3.11.6 (2025-09-29)
 
 Tests:
diff --git a/Makefile b/Makefile
index 615261f54..18e80a245 100644
--- a/Makefile
+++ b/Makefile
@@ -135,7 +135,7 @@ $(GITHUB_PAGES): $(HTML_USER_MANUAL)
 
 # This target downloads Unicode Character Database files.
 $(UNICODE_DATA):
-	wget https://www.unicode.org/Public/16.0.0/ucd/$@
+	wget https://www.unicode.org/Public/17.0.0/ucd/$@
 
 # This target extracts the source files out of the DTX archive.
 $(EXTRACTABLES): $(INSTALLER) $(DTXARCHIVE) $(UNICODE_DATA)
diff --git a/markdown.dtx b/markdown.dtx
index 94dcb9f23..6cc3e7b9a 100644
--- a/markdown.dtx
+++ b/markdown.dtx
@@ -39520,16 +39520,14 @@ end
     \@@_if_option:nTF
       { experimental }
       {
-        \msg_error:nnn
+        \msg_error:nn
           { markdown }
           { latex-markdown-star-deprecated }
-          { #1 }
       }
       {
-        \msg_warning:nnn
+        \msg_warning:nn
           { markdown }
           { latex-markdown-star-deprecated }
-          { #1 }
       }
     \@@_setup:n
       { #1 }
@@ -39625,10 +39623,9 @@ end
               }
           }
           {
-            \msg_error:nnn
+            \msg_error:nn
               { markdown }
               { latex-theme-after-preamble }
-              { #1 }
           }
 %    \end{macrocode}
 % \begin{markdown}