QTextCodec and ICU libraries

I have a compiled version of QT without the ICU libraries to reduce the size of a particular project. Everything has been working fine until I recently added some QTextCodec functionality, which crashes the application due to QCore exceptions.

The curious thing is that using a toUnicode function:

Code:

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QTextCodec::codecForName("IBM 437")->toUnicode(buf);

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crashes, but using a fromUnicode

Code:

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QByteArray data = QTextCodec::codecForName("IBM 437")->fromUnicode(str);

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is just fine.

Is this intended behaviour? Is my conclusion correct that any call to toUnicode requires ~20mb of libraries be included with the executable?