diff --git a/CHANGES b/CHANGES
index 3cda37d..8eba463 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,5 +1,8 @@
 Version 0.4
 -----------
+05/09/2020 Changed the internal names used for EBNF rules to make them
+           a bit easier to debug in the parser.out file.
+
 03/06/2020 Added experimental support for EBNF repetition and optional
            syntax.  For example, here is a rule for a comma-separated
            expression list:
diff --git a/sly/yacc.py b/sly/yacc.py
index 1bcf7f3..c7f0d99 100644
--- a/sly/yacc.py
+++ b/sly/yacc.py
@@ -1613,23 +1613,19 @@ def _replace_ebnf_optional(syms):
 # Generate grammar rules for repeated items
 _gencount = 0
 
-def _unique_names(names):
-    from collections import defaultdict, Counter
-    counts = Counter(names)
-    indices = defaultdict(int)
-    newnames = []
-    for name in names:
-        if counts[name] == 1:
-            newnames.append(name)
-        else:
-            newnames.append(f'{name}{indices[name]}')
-            indices[name] += 1
-    return newnames
-
 # Dictionary mapping name aliases generated by EBNF rules.
 
 _name_aliases = { }
 
+def _sanitize_symbols(symbols):
+    for sym in symbols:
+        if sym.startswith("'"):
+            yield str(hex(ord(sym[1])))
+        elif sym.isidentifier():
+            yield sym
+        else:
+            yield sym.encode('utf-8').hex()
+            
 def _generate_repeat_rules(symbols):
     '''
     Symbols is a list of grammar symbols [ symbols ]. This
@@ -1654,9 +1650,10 @@ def _generate_repeat_rules(symbols):
     '''
     global _gencount
     _gencount += 1
-    name = f'_{_gencount}_repeat'
-    oname = f'_{_gencount}_items'
-    iname = f'_{_gencount}_item'
+    basename = f'_{_gencount}_' + '_'.join(_sanitize_symbols(symbols))
+    name = f'{basename}_repeat'
+    oname = f'{basename}_items'
+    iname = f'{basename}_item'
     symtext = ' '.join(symbols)
 
     _name_aliases[name] = symbols
@@ -1709,7 +1706,8 @@ def _generate_optional_rules(symbols):
     '''
     global _gencount
     _gencount += 1
-    name = f'_{_gencount}_optional'
+    basename = f'_{_gencount}_' + '_'.join(_sanitize_symbols(symbols))
+    name = f'{basename}_optional'
     symtext = ' '.join(symbols)
     
     _name_aliases[name] = symbols