Since 2.8.6 it reads the files with default charset: https://github.com/codehaus-plexus/plexus-compiler/blob/0df7395b3922cffd043dd25b3d88875bf802e982/plexus-compilers/plexus-compiler-eclipse/src/main/java/org/codehaus/plexus/compiler/eclipse/EclipseJavaCompiler.java#L328 Try compiling the attached file when default charset is ISO-8859-1. [Utf.java.txt](https://github.com/codehaus-plexus/plexus-compiler/files/4624367/Utf.java.txt)