diff --git a/grub-core/script/yylex.l b/grub-core/script/yylex.l
index 95b219170..7b44c37b7 100644
--- a/grub-core/script/yylex.l
+++ b/grub-core/script/yylex.l
@@ -91,7 +91,7 @@ typedef size_t yy_size_t;
 #define stdin  0
 #define stdout 0
 
-#define fprintf(...) 0
+#define fprintf(...) (void)0
 #define exit(...) grub_fatal("fatal error in lexer")
 #endif