diff --git a/VM/src/lstrlib.cpp b/VM/src/lstrlib.cpp
index bbed2d5a..69fd0d67 100644
--- a/VM/src/lstrlib.cpp
+++ b/VM/src/lstrlib.cpp
@@ -1034,8 +1034,13 @@ static int str_format(lua_State* L)
             }
             case '*':
             {
-                sprintf(buff, "%s", luaL_tolstring(L, arg, NULL));
-                break;
+                size_t length;
+                const char* string = luaL_tolstring(L, arg, &length);
+
+                luaL_reservebuffer(&b, length, -1);
+                luaL_addlstring(&b, string, length);
+
+                continue; /* skip the `addsize' at the end */
             }
             default:
             { /* also treat cases `pnLlh' */
diff --git a/tests/conformance/strings.lua b/tests/conformance/strings.lua
index 30732e85..f07fb4bd 100644
--- a/tests/conformance/strings.lua
+++ b/tests/conformance/strings.lua
@@ -143,6 +143,9 @@ assert(pcall(function()
 	string.format("%* %* %*", return_two_nils())
 end) == false)
 
+assert(string.format("%*", "a\0b\0c") == "a\0b\0c")
+assert(string.format("%*", string.rep("doge", 3000)) == string.rep("doge", 3000))
+
 assert(loadstring("return 1\n--comentário sem EOL no final")() == 1)