diff --git a/src/gui/lua/lua_misc.cpp b/src/gui/lua/lua_misc.cpp
index 03b396975..072b44802 100644
--- a/src/gui/lua/lua_misc.cpp
+++ b/src/gui/lua/lua_misc.cpp
@@ -118,12 +118,12 @@ int CLuaInstMisc::strSub(lua_State *L)
 		return 1;
 	}
 	const char *s1;
-	int pos=0, len=std::string::npos;
+	size_t pos=0, len=std::string::npos;
 	std::string ret="";
 	s1 = luaL_checkstring(L, 2);
 	pos = luaL_checkint(L, 3);
 	if (numargs > 3)
-		len = luaL_checkint(L, 4);
+		len = (size_t)luaL_checkint(L, 4);
 
 	std::string str(s1);
 	ret = str.substr(pos, len);
diff --git a/src/gui/lua/luainstance.h b/src/gui/lua/luainstance.h
index 96cce8fee..c77fc2b5b 100644
--- a/src/gui/lua/luainstance.h
+++ b/src/gui/lua/luainstance.h
@@ -31,7 +31,7 @@ extern "C" {
 #include "luainstance_helpers.h"
 
 #define LUA_API_VERSION_MAJOR 1
-#define LUA_API_VERSION_MINOR 25
+#define LUA_API_VERSION_MINOR 26
 
 /* inspired by Steve Kemp http://www.steve.org.uk/ */
 class CLuaInstance