[rules-users] no such field error

I'm converting my project to 4.0 M2. I'm having this problem and I wonder if it looks familiar to anyone... Exception in thread "main" java.lang.NoSuchFieldError: type at org.drools.lang.DRLLexer.mPACKAGE(DRLLexer.java:1186) at org.drools.lang.DRLLexer.mTokens(DRLLexer.java:2456) at org.antlr.runtime.Lexer.nextToken(Lexer.java:86) at org.antlr.runtime.CommonTokenStream.fillBuffer(CommonTokenStream.java:94 ) at org.antlr.runtime.CommonTokenStream.LT(CommonTokenStream.java:237) at org.antlr.runtime.CommonTokenStream.LA(CommonTokenStream.java:299) at org.drools.lang.DRLParser.prolog(DRLParser.java:362) at org.drools.lang.DRLParser.compilation_unit(DRLParser.java:293) at org.drools.compiler.DrlParser.compile(DrlParser.java:137) at org.drools.compiler.DrlParser.parse(DrlParser.java:56) at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java :155) at test.hxr.TestCompileDrl.testCompileAndExecute(TestCompileDrl.java:76) I know it's probably a library or resource version mismatch but I can't seem chase it down...