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@@ -144,6 +144,10 @@ is not optimal and was only fixed in llvm 9.
 You can set this with AFL_LLVM_NOT_ZERO=1
 See [README.neverzero.md](README.neverzero.md)
 
+Support for thread safe counters has been added for mode LLVM CLASSIC.
+Activate it with `AFL_LLVM_THREADSAFE_INST=1`. The tradeoff is better precision in 
+multi threaded apps for a slightly higher instrumentation overhead.
+
 ## 4) Snapshot feature
 
 To speed up fuzzing you can use a linux loadable kernel module which enables