diff --git a/appview/pages/markup/format.go b/appview/pages/markup/format.go
--- a/appview/pages/markup/format.go
+++ b/appview/pages/markup/format.go
@@ -17,7 +17,7 @@ var FileTypePatterns = map[Format]*regexp.Regexp{
 	FormatMarkdown: regexp.MustCompile(`(?i)\.(md|markdown|mdown|mkdn|mkd)$`),
 }
 
-var ReadmePattern = regexp.MustCompile(`(?i)^readme(?:[._-].+)?$`)
+var ReadmePattern = regexp.MustCompile(`(?i)^readme(?:\.[^.]+)?$`)
 
 // IsReadmeFile reports whether name/mode identifies a readme blob. The git
 // mode is checked so directories or symlinks named "readme" are filtered out.
diff --git a/appview/pages/markup/format_test.go b/appview/pages/markup/format_test.go
--- a/appview/pages/markup/format_test.go
+++ b/appview/pages/markup/format_test.go
@@ -30,13 +30,16 @@ // as the README blob; tree handlers used to fetch it and 503.
 		{"readme", dirMode, false},
 		{"README.md", dirMode, false},
 
-		// readme is matched by convention, not by renderable format —
+		// readme is matched by convention, not by renderable format;
 		// unsupported markup falls through to plaintext in GetFormat.
 		{"README.rst", fileMode, true},
 		{"README.org", fileMode, true},
-		{"readme-old", fileMode, true},
-		{"readme_legacy", fileMode, true},
+		{"README.asciidoc", fileMode, true},
+		{"README.foo", fileMode, true},
 
+		{"README.Music.md", fileMode, false},
+		{"readme-old", fileMode, false},
+		{"readme_legacy", fileMode, false},
 		{"notreadme.md", fileMode, false},
 		{"READMEISH", fileMode, false},
 		{"README.md", "", false},