diff --git a/expr/expr.cc b/expr/expr.cc
index 9459620..3412c8f 100644
--- a/expr/expr.cc
+++ b/expr/expr.cc
@@ -55,7 +55,9 @@ enum token_type {
 };
 
 extern "C" {
+#if 0
 long long yylval = 0;
+#endif
 #define YYSTYPE long long
 #include "expr-parse.h"