diff --git a/Source/GSFastEnumeration.h b/Source/GSFastEnumeration.h
new file mode 100644
index 000000000..1dd90df9d
--- /dev/null
+++ b/Source/GSFastEnumeration.h
@@ -0,0 +1,38 @@
+
+#ifdef __clang__
+#define FOR_IN(type, var, collection) \
+	for (type var in collection)\
+	{
+#define END_FOR_IN(collection) }
+#else
+void objc_enumerationMutation(id);
+#define FOR_IN(type, var, c) \
+do\
+{\
+	type var;\
+	NSFastEnumerationState gs_##c##_enumState = { 0 };\
+	id gs_##c##_items[16];\
+	unsigned long gs_##c##_limit = \
+		[c countByEnumeratingWithState: &gs_##c##_enumState \
+		                       objects: gs_##c##_items \
+		                         count: 16];\
+	if (gs_##c##_limit)\
+	{\
+		unsigned long gs_startMutations = *gs_##c##_enumState.mutationsPtr;\
+		do {\
+			unsigned long gs_##c##counter = 0;\
+			do {\
+				if (gs_startMutations != *gs_##c##_enumState.mutationsPtr)\
+				{\
+					objc_enumerationMutation(c);\
+				}\
+				var = gs_##c##_enumState.itemsPtr[gs_##c##counter++];\
+
+#define END_FOR_IN(c) \
+			} while (gs_##c##counter < gs_##c##_limit);\
+		} while ((gs_##c##_limit = [c countByEnumeratingWithState: &gs_##c##_enumState\
+		                                                  objects: gs_##c##_items\
+		                                                    count: 16]));\
+	}\
+} while(0);
+#endif