diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3403fc6..5aef8e0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,5 +1,5 @@
 cmake_minimum_required(VERSION 3.25)
-project(blt-gp VERSION 0.0.119)
+project(blt-gp VERSION 0.0.120)
 
 include(CTest)
 
diff --git a/include/blt/gp/program.h b/include/blt/gp/program.h
index d818ed5..16092cc 100644
--- a/include/blt/gp/program.h
+++ b/include/blt/gp/program.h
@@ -541,7 +541,7 @@ namespace blt::gp
             population_stats current_stats{};
             population_t next_pop;
             std::atomic_uint64_t current_generation = 0;
-            bool fitness_should_exit = false;
+            std::atomic_bool fitness_should_exit = false;
             
             blt::u64 seed;
             prog_config_t config{};