diff --git a/data/lalr1.cc b/data/lalr1.cc
index 82e68244..308290ad 100644
--- a/data/lalr1.cc
+++ b/data/lalr1.cc
@@ -335,9 +335,9 @@ do {					\
 #else /* !]b4_api_PREFIX[DEBUG */
 
 # define YYCDEBUG if (false) std::cerr
-# define YY_SYMBOL_PRINT(Title, Type, Value, Location)
-# define YY_REDUCE_PRINT(Rule)
-# define YY_STACK_PRINT()
+# define YY_SYMBOL_PRINT(Title, Type, Value, Location) YYUSE(Type)
+# define YY_REDUCE_PRINT(Rule)        static_cast<void>(0)
+# define YY_STACK_PRINT()             static_cast<void>(0)
 
 #endif /* !]b4_api_PREFIX[DEBUG */