diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8e090d4..d63341f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -27,7 +27,7 @@ macro(compile_options target_name)
     sanitizers(${target_name})
 endmacro()
 
-project(blt-gp VERSION 0.5.7)
+project(blt-gp VERSION 0.5.8)
 
 include(CTest)
 
diff --git a/lib/blt b/lib/blt
index 6cdfab3..90cf177 160000
--- a/lib/blt
+++ b/lib/blt
@@ -1 +1 @@
-Subproject commit 6cdfab39cfc1e10fe8fe7a34863963d01620bdb3
+Subproject commit 90cf177c57f542ecdd132eaa6af0f1945ce8fe96
diff --git a/tests/serialization_test.cpp b/tests/serialization_test.cpp
index 9be2246..3512c56 100644
--- a/tests/serialization_test.cpp
+++ b/tests/serialization_test.cpp
@@ -66,7 +66,7 @@ bool fitness_function(const tree_t& current_tree, fitness_t& fitness, size_t)
     {
         BLT_GP_UPDATE_CONTEXT(fitness_case);
         auto val = current_tree.get_evaluation_ref<float>(fitness_case);
-        const auto diff = std::abs(fitness_case.y - val.get().value());
+        const auto diff = std::abs(fitness_case.y - val.get());
         if (diff < value_cutoff)
         {
             fitness.raw_fitness += diff;