diff --git a/src/hlua.c b/src/hlua.c
index 8bc831944..f99bdf9d2 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -741,6 +741,8 @@ __LJMP int hlua_lua2arg_check(lua_State *L, int first, struct arg *argp,
 			break;
 
 		case ARGT_IPV4:
+			if (argp[idx].type != ARGT_STR)
+				WILL_LJMP(luaL_argerror(L, first + idx, "string expected"));
 			memcpy(trash.area, argp[idx].data.str.area,
 			       argp[idx].data.str.data);
 			trash.area[argp[idx].data.str.data] = 0;
@@ -759,6 +761,8 @@ __LJMP int hlua_lua2arg_check(lua_State *L, int first, struct arg *argp,
 			break;
 
 		case ARGT_IPV6:
+			if (argp[idx].type != ARGT_STR)
+				WILL_LJMP(luaL_argerror(L, first + idx, "string expected"));
 			memcpy(trash.area, argp[idx].data.str.area,
 			       argp[idx].data.str.data);
 			trash.area[argp[idx].data.str.data] = 0;