diff -up qtbase-opensource-src-5.6.0-beta/src/tools/moc/main.cpp.moc_WORDSIZE qtbase-opensource-src-5.6.0-beta/src/tools/moc/main.cpp
--- qtbase-opensource-src-5.6.0-beta/src/tools/moc/main.cpp.moc_WORDSIZE	2015-12-04 18:05:24.000000000 -0600
+++ qtbase-opensource-src-5.6.0-beta/src/tools/moc/main.cpp	2015-12-15 20:57:55.554485416 -0600
@@ -184,6 +184,10 @@ int runMoc(int argc, char **argv)
     Moc moc;
     pp.macros["Q_MOC_RUN"];
     pp.macros["__cplusplus"];
+    Macro macro;
+    macro.symbols = Preprocessor::tokenize(QByteArray::number(Q_PROCESSOR_WORDSIZE*8), 1, Preprocessor::TokenizeDefine);
+    macro.symbols.removeLast(); // remove the EOF symbol
+    pp.macros.insert("__WORDSIZE", macro);
 
     // Don't stumble over GCC extensions
     Macro dummyVariadicFunctionMacro;