diff --git a/docs/cton_lexer.py b/docs/cton_lexer.py
index 0567b748c7..0df2e6208a 100644
--- a/docs/cton_lexer.py
+++ b/docs/cton_lexer.py
@@ -2,9 +2,12 @@
 #
 # Pygments lexer for Cretonne.
 
-from pygments.lexer import RegexLexer, bygroups
+from pygments.lexer import RegexLexer, bygroups, words
 from pygments.token import *
 
+def keywords(*args):
+    return words(args, prefix=r'\b', suffix=r'\b')
+
 class CretonneLexer(RegexLexer):
     name = 'Cretonne'
     aliases = ['cton']
@@ -13,19 +16,30 @@ class CretonneLexer(RegexLexer):
     tokens = {
         'root': [
             (r';.*?$', Comment.Single),
-            (r'\b(function|entry)\b', Keyword),
-            (r'\b(align)\b', Name.Attribute),
+            # Strings are in double quotes, support \xx escapes only.
+            (r'"([^"\\]+|\\[0-9a-fA-F]{2})*"', String),
+            # A naked function name following 'function' is also a string.
+            (r'\b(function)([ \t]+)(\w+)\b', bygroups(Keyword, Whitespace, String.Symbol)),
+            # Numbers.
+            (r'[-+]?0[xX][0-9a-fA-F]+', Number.Hex),
+            (r'[-+]?0[xX][0-9a-fA-F]*\.[0-9a-fA-F]*([pP]\d+)?', Number.Hex),
+            (r'[-+]?\d+\.\d+([eE]\d+)?', Number.Float),
+            (r'[-+]?\d+', Number.Integer),
+            # Reserved words.
+            (keywords('function', 'entry'), Keyword),
+            # Known attributes.
+            (keywords('align'), Name.Attribute),
             # Well known value types.
             (r'\b(bool|i\d+|f32|f64)(x\d+)?\b', Keyword.Type),
-            (r'\d+', Number.Integer),
-            (r'0[xX][0-9a-fA-F]+', Number.Hex),
             # v<nn> = value
             # ss<nn> = stack slot
             (r'(v|ss)\d+', Name.Variable),
             # ebb<nn> = extended basic block
             (r'(ebb)\d+', Name.Label),
+            # Match instruction names in context.
             (r'(=)( *)([a-z]\w*)', bygroups(Operator, Whitespace, Name.Function)),
             (r'^( +)([a-z]\w*\b)(?! *[,=])', bygroups(Whitespace, Name.Function)),
+            # Other names: results and arguments
             (r'[a-z]\w*', Name),
             (r'->|=|:', Operator),
             (r'[{}(),.]', Punctuation),