diff --git a/web/index.html b/web/index.html
index 2ecbe34..df57f6a 100644
--- a/web/index.html
+++ b/web/index.html
@@ -1237,6 +1237,8 @@ macro is a function from <code>Form</code> to <code>Form</code>, which needs
     "declare declare-c import package let if when unless cond do and or not while " +
     "until dotimes match set return some try defer signal error handler-bind " +
     "restart-case invoke-restart fn quote defmacro gensym").split(" "));
+  // Capitalised names are types; these are the ones that are not capitalised.
+  var TYPES = new Set(("i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 bool string").split(" "));
   var TOKEN = /(;[^\n]*)|("(?:\\.|[^"\\])*")|(\\[A-Za-z0-9]+)|(:[A-Za-z][\w?!*<>=+-]*)|(\b0[xX][0-9a-fA-F]+\b|\b\d[\d.]*\b)|([A-Za-z][\w*?!<>=./+-]*)/g;
   function esc(s) {
     return s.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;");
@@ -1253,7 +1255,8 @@ macro is a function from <code>Form</code> to <code>Form</code>, which needs
         if (num)     return '<span class="n">' + m + "</span>";
         if (word) {
           if (FORMS.has(word)) return '<span class="f">' + m + "</span>";
-          if (/^[A-Z]/.test(word)) return '<span class="t">' + m + "</span>";
+          if (TYPES.has(word) || /^[A-Z]/.test(word))
+            return '<span class="t">' + m + "</span>";
         }
         return m;
       });