diff --git a/llimits.h b/llimits.h
index 246dca8b..03cc51cb 100644
--- a/llimits.h
+++ b/llimits.h
@@ -70,11 +70,24 @@ typedef signed char ls_byte;
 
 
 /*
-** conversion of pointer to unsigned integer:
-** this is for hashing only; there is no problem if the integer
-** cannot hold the whole pointer value
+** conversion of pointer to unsigned integer: this is for hashing only;
+** there is no problem if the integer cannot hold the whole pointer
+** value. (In strict ISO C this may cause undefined behavior, but no
+** actual machine seems to bother.)
 */
-#define point2uint(p)	((unsigned int)((size_t)(p) & UINT_MAX))
+#if !defined(LUA_USE_C89) && defined(__STDC_VERSION__) && \
+    __STDC_VERSION__ >= 199901L
+#include <stdint.h>
+#if defined(UINTPTR_MAX)  /* even in C99 this type is optional */
+#define L_P2I	uintptr_t
+#else  /* no 'intptr'? */
+#define L_P2I	uintmax_t  /* use the largerst available integer */
+#endif
+#else  /* C89 option */
+#define L_P2I	size_t
+#endif
+
+#define point2uint(p)	((unsigned int)((L_P2I)(p) & UINT_MAX))
 
 
 
diff --git a/loslib.c b/loslib.c
index 854dcf69..89ac06bc 100644
--- a/loslib.c
+++ b/loslib.c
@@ -138,12 +138,21 @@
 /* }================================================================== */
 
 
+#if !defined(l_system)
+#if defined(LUA_USE_IOS)
+/* Despite claiming to be ISO C, iOS does not implement 'system'. */
+#define l_system(cmd) ((cmd) == NULL ? 0 : -1)
+#else
+#define l_system(cmd)	system(cmd)  /* default definition */
+#endif
+#endif
+
 
 static int os_execute (lua_State *L) {
   const char *cmd = luaL_optstring(L, 1, NULL);
   int stat;
   errno = 0;
-  stat = system(cmd);
+  stat = l_system(cmd);
   if (cmd != NULL)
     return luaL_execresult(L, stat);
   else {
diff --git a/luaconf.h b/luaconf.h
index e4650fbc..137103ed 100644
--- a/luaconf.h
+++ b/luaconf.h
@@ -70,6 +70,12 @@
 #endif
 
 
+#if defined(LUA_USE_IOS)
+#define LUA_USE_POSIX
+#define LUA_USE_DLOPEN
+#endif
+
+
 /*
 @@ LUAI_IS32INT is true iff 'int' has (at least) 32 bits.
 */