missing header

Index: src/Core/OldSchoolPropertyListWriting.m
--- src/Core/OldSchoolPropertyListWriting.m.orig
+++ src/Core/OldSchoolPropertyListWriting.m
@@ -20,6 +20,9 @@
 
 #import "OldSchoolPropertyListWriting.h"
 
+#include <assert.h>
+
+
 
 static BOOL IsFloatingPoint(NSNumber *number);
 static void AppendNewLineAndIndent(NSMutableString *ioString, unsigned indentDepth);
