diff --git a/src/parse-gram.c b/src/parse-gram.c
index cc42b0d0..8215a943 100644
--- a/src/parse-gram.c
+++ b/src/parse-gram.c
@@ -119,7 +119,7 @@ static void version_check (location const *loc, char const *version);
 
 static void gram_error (location const *, char const *);
 
-/// A string that describes a char (e.g., 'a' -> "'a'").
+/* A string that describes a char (e.g., 'a' -> "'a'").  */
 static char const *char_name (char);
 
 #line 126 "src/parse-gram.c" /* yacc.c:357  */
diff --git a/src/parse-gram.y b/src/parse-gram.y
index 2c84cb1c..e889eb5e 100644
--- a/src/parse-gram.y
+++ b/src/parse-gram.y
@@ -46,7 +46,7 @@ static void version_check (location const *loc, char const *version);
 
 static void gram_error (location const *, char const *);
 
-/// A string that describes a char (e.g., 'a' -> "'a'").
+/* A string that describes a char (e.g., 'a' -> "'a'").  */
 static char const *char_name (char);
 %}