A technique is presented here for improving the compression achieved with any linear decompressor by adding a small non-linear decoder that exploits bit-wise and pattern-wise correlation present in test vectors. The proposed non-linear decoder has a regular and compact structure and allows continuous-flow decompression. It has a very important feature which is that its design does not depend on the test data. This simplifies the design flow and allows the decoder to be reused when testing multiple cores on a chip. Experimental results show that combining a linear decompressor with the small non-linear decoder proposed here significantly improves the overall compression.