diff --git a/src/lib_math.c b/src/lib_math.c
index 3a56514b..a1d8a618 100644
--- a/src/lib_math.c
+++ b/src/lib_math.c
@@ -209,7 +209,7 @@ LUALIB_API int luaopen_math(lua_State *L)
   rs = (RandomState *)lua_newuserdata(L, sizeof(RandomState));
   rs->valid = 0;  /* Use lazy initialization to save some time on startup. */
   LJ_LIB_REG(L, LUA_MATHLIBNAME, math);
-#if defined(LUA_COMPAT_MOD)
+#if defined(LUA_COMPAT_MOD) && !LJ_52
   lua_getfield(L, -1, "fmod");
   lua_setfield(L, -2, "mod");
 #endif
diff --git a/src/lib_string.c b/src/lib_string.c
index 6d0b0a04..d894f9f4 100644
--- a/src/lib_string.c
+++ b/src/lib_string.c
@@ -857,7 +857,7 @@ LUALIB_API int luaopen_string(lua_State *L)
   GCtab *mt;
   global_State *g;
   LJ_LIB_REG(L, LUA_STRLIBNAME, string);
-#if defined(LUA_COMPAT_GFIND)
+#if defined(LUA_COMPAT_GFIND) && !LJ_52
   lua_getfield(L, -1, "gmatch");
   lua_setfield(L, -2, "gfind");
 #endif