diff --git a/include/bx/blockalloc.h b/include/bx/blockalloc.h
index e7d0704..7597653 100644
--- a/include/bx/blockalloc.h
+++ b/include/bx/blockalloc.h
@@ -64,7 +64,7 @@ namespace bx
 		void free(void* _obj)
 		{
 			uint16_t index = getIndex(_obj);
-			BX_CHECK(index >= 0 && index < m_num, "index %d, m_num %d", index, m_num);
+			BX_CHECK(index < m_num, "index %d, m_num %d", index, m_num);
 
 			*( (uint16_t*)_obj) = m_freeIndex;
 			m_freeIndex = index;
diff --git a/include/bx/platform.h b/include/bx/platform.h
index 18d36a2..7e8e290 100644
--- a/include/bx/platform.h
+++ b/include/bx/platform.h
@@ -71,6 +71,8 @@
 #	error "BX_PLATFORM_* is not defined!"
 #endif //
 
+#define BX_PLATFORM_POSIX (BX_PLATFORM_NACL || BX_PLATFORM_ANDROID || BX_PLATFORM_LINUX || BX_PLATFORM_OSX || BX_PLATFORM_IOS)
+
 // http://sourceforge.net/apps/mediawiki/predef/index.php?title=Architectures
 #if defined(__arm__)
 #	undef BX_CPU_ARM
diff --git a/include/bx/sem.h b/include/bx/sem.h
index 8ca50ab..118e4f7 100644
--- a/include/bx/sem.h
+++ b/include/bx/sem.h
@@ -8,9 +8,7 @@
 
 #include "bx.h"
 
-#define BX_SEM_CONFIG_POSIX (BX_PLATFORM_NACL || BX_PLATFORM_ANDROID || BX_PLATFORM_LINUX)
-
-#if BX_SEM_CONFIG_POSIX
+#if BX_PLATFORM_POSIX
 #	include <semaphore.h>
 #	include <time.h>
 #elif BX_PLATFORM_WINDOWS || BX_PLATFORM_XBOX360
@@ -19,7 +17,7 @@
 
 namespace bx
 {
-#if BX_SEM_CONFIG_POSIX
+#if BX_PLATFORM_POSIX
 	class Semaphore
 	{
 	public: