diff --git a/src/oniguruma/lonig.c b/src/oniguruma/lonig.c
index d97f922..d622445 100644
--- a/src/oniguruma/lonig.c
+++ b/src/oniguruma/lonig.c
@@ -46,7 +46,7 @@ static void checkarg_compile (lua_State *L, int pos, TArgComp *argC);
   lua_pushlstring (L, (text) + ALG_SUBBEG(ud,n), ALG_SUBLEN(ud,n))
 
 #define ALG_PUSHSUB_OR_FALSE(L,ud,text,n) \
-  (ALG_SUBVALID(ud,n) ? ALG_PUSHSUB (L,ud,text,n) : lua_pushboolean (L,0))
+  (ALG_SUBVALID(ud,n) ? (void) ALG_PUSHSUB (L,ud,text,n) : lua_pushboolean (L,0))
 
 #define ALG_PUSHSTART(L,ud,offs,n)   lua_pushinteger(L, (offs) + ALG_SUBBEG(ud,n) + 1)
 #define ALG_PUSHEND(L,ud,offs,n)     lua_pushinteger(L, (offs) + ALG_SUBEND(ud,n))